biology

Required readings

Lewis, R. 2018. Human Genetics, Concepts and Applications,13th ed. McGraw-Hill.

Read Chapters 9, 10, and 11 in the textbook.

Read M3 Content Guides. 1, 2, 3,

1. DNA and RNA

For a long time many scientists believed that proteins must be the hereditary molecules because they are large and complex. By the mid-1900s, however, DNA was confirmed to be the genetic molecule of heredity. Its deceptive simplicity blinded many early researchers to the fact that the key to its complexity is in the organization of its few simple nitrogenous bases.

DNA is composed of nucleotides, each containing a deoxyribose sugar (a pentagon-shaped carbon ring), a phosphate group (a phosphorus atom surrounded by four oxygens), and one of four different nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G).

Alternating sugars and phosphates form the sides of the twisted ladder-like DNA double helix. The two strands are antiparallel, which means they run in opposite directions, chemically speaking: one in a 3’-to-5’ direction and the other in a 5’-to-3’ direction (referring to the specific numbered carbons in the sugar rings).

The sugars and phosphates form the outside of the molecule. Towards the inside of the molecule, nitrogenous bases form the “rungs” of the ladder. Hydrogen bonds form between opposite nitrogenous bases (A—T, C—G): A always attaches with two hydrogen bonds to T, and C always attaches with three hydrogen bonds to G. A and G are purines, which are larger molecules than C and T, which are pyrimidines. Since each rung is always composed of one purine paired with one pyrimidine, the length of the rungs is always consistent, giving the DNA molecule stability. Single hydrogen bonds are weak, but collectively they are sufficient to hold the two complementary strands together.

DNA replication is a complex biochemical reaction involving several different enzymes responsible for initiation, elongation, and termination of the new strand, as well as mechanisms for proofreading the newly created strands, mechanisms for repairing any errors detected, and mechanisms for ligating (joining) any loose ends created. DNA replication is semiconservative. The two parent strands separate and each serves as a template for a newly synthesized strand.

Various protein enzymes carry out the following functions:

The two DNA strands begin to separate at a replication fork.

Helicases unwind and open up the helix.

DNA gyrase cuts, untwists, and reseals spots along the DNA to relax coiling tension.

An RNA primer is necessary to begin replication--it provides the first 3’ end for the first new DNA nucleotide to attach to.

DNA Polymerase elongates the chain in the 5’-to-3’ direction by adding new nucleotides.

Because the two DNA strands are antiparallel (run in opposite directions) synthesis in the 5’-to-3’ direction is continuous, but synthesis in the 3’-to-5’ direction is discontinuous. DNA nucleotides can only be added in the 5’-to-3’ direction; therefore, a continuous strand will be formed in that direction (along the leading strand). On the opposite strand (the lagging strand), numerous discontinuous short segments, called Okazaki fragments, are initiated and are created in the opposite direction. An enzyme named DNA ligase fills in the gaps between the Okazaki fragments.

RNA primers must be removed and proofreading occurs to correct errors. Polymerase enzymes can briefly “back up” in a 3’-to-5’ direction to cut out and replace an incorrect nucleotide.

RNA is a nucleic acid similar to DNA with the following differences:

RNA is usually single stranded,

The sugar in RNA is ribose, instead of deoxyribose, and

RNA contains uracil (U) instead of thymine.

RNA is manufactured along DNA in a process called transcription, which will be discussed in detail in the next content guide. Individual RNA nucleotides attach to the DNA of a gene that functions in producing a particular type of RNA. Hydrogen bonding is the same as in DNA replication (C with G, G with C, A with T), but in RNA uracil bonds with adenine (U with A).

There are three main types of RNA: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). These RNA molecules interact during the processes of transcription and translation that result in the manufacturing of proteins (protein synthesis). In addition to these three main types of RNA there are many other small forms of RNA. Research into the functions of these micro RNAs is intense right now and we are on the brink of many exciting new medical breakthroughs using these tiny molecules.

2. Making Protien

There are three main types of RNA that work together to use the information coded in the DNA to produce proteins needed by the cell:

1) Messenger RNA (mRNA) first obtains the “message” in a gene by being created along the length of the gene during transcription. Remember that the message is transferred intact because of specific base pairing. (If you are given the sequence of mRNA nucleotides, you can easily decode the sequence of DNA nucleotides in the gene).

Messenger RNA must leave the nucleus and attach to a ribosome in order to participate in the production of a particular protein. The genetic code is written in three-letter words called codons along the mRNA strand. Each codon is composed of three nucleotides that specify a particular amino acid or a termination signal.

2) Ribosomal RNA (rRNA) is transcribed along the DNA of multiple copies of genes that function to mass-produce these molecules that make up the structure of ribosomes. Ribosomes are the “protein factories” of the cell, and are extremely numerous. Ribosomal RNA is the largest type of RNA molecule, and produces two subunits, one large and one small, which remain apart until they combine in order to produce proteins by associating with mRNA and tRNA.

3) Transfer RNA (tRNA) is the smallest RNA molecule. Its function is to transport amino acids to the ribosome, where they are inserted into the correct position in the growing polypeptide chain of amino acids being produced. Transfer RNA molecules must therefore have one end that attaches to a specific amino acid (the amino acid binding site) and another end that attaches to the codon on the mRNA molecule (the anticodon loop). The anticodon on the tRNA molecule is composed of three nucleotides that are complementary to a particular codon on the mRNA strand.

Now, let’s go over the steps involved in manufacturing a protein from directions contained within the genetic code of the DNA of a gene:

Transcription is the first part of the process. An mRNA strand will be created along the DNA template strand through transcription: the DNA helix unwinds and its two strands separate to allow access to the gene on the template strand; then RNA polymerase catalyzes the sequential attachment of new complementary RNA nucleotides, creating the mRNA strand that now contains the genetic code from this gene.

In a eukaryotic cell, once the mRNA molecule is finished transcribing the gene and detaches from the DNA it must move out of the nucleus through the double nuclear membrane to a ribosome in the cytoplasm. The RNA is termed pre-mRNA when it is released from the DNA, because it needs to undergo further processing before it is ready to translate a protein at the ribosome.

Posttranscriptional RNA processing includes the addition of a 7mG cap to the 5’ end and the addition of a poly-A tail to the 3’ end (the cap and tail seem to protect the mRNA from being degraded, and they may assist the mRNA through the nuclear membrane). Splicing is the next step. Introns are intervening sequences that are not used to translate the protein and must be removed before the mRNA attaches to the ribosome. Exons are the stretches of mRNA that will be expressed and translate the protein at the ribosome. Alternative splicing may explain why the sequencing of the human genome revealed far fewer genes than were expected (about 30,000). Many of our genes are capable of producing several different proteins each, depending on how they are spliced. This may also partially explain the function of some introns (they may be necessary for some proteins, but not for others).

An mRNA molecule will be available to translate proteins for a few hours before being degraded by the cell. If the cell continues to need the protein product, more mRNA will be transcribed from the DNA. If the protein is no longer needed, no metabolically expensive excess will be produced.

Translation: the production of proteins from directions on an mRNA strand that transcribed this information from a gene (a stretch of DNA along a chromosome) is termed translation because the language of nucleic acids (sequences of nucleotides) is translated to the language of proteins (sequences of amino acids). Translation occurs on individual ribosomes, where large ribosomal subunits combine with small ribosomal subunits, forming “workbenches” for the manufacture of proteins. At each ribosome, codons along the mRNA can temporarily attach to anticodons of tRNA molecules that bring specific amino acids to the ribosomal complex. The sequence of amino acids that are hooked together by peptide bonds follows the sequence of nucleotides along the mRNA strand, which carries the genetic code from the DNA of the gene. Codons (triplet code words) on the mRNA will determine the sequence of amino acids ultimately linked together at a ribosome to create the protein chain.

3.Gene Expression and Epigenetics

The fact that mRNA has a short lifespan is important in giving the cell precise control over the amount of each protein that is transcribed at any one time. If only a small amount is needed, no more mRNA will be transcribed along the gene. If more protein is required, mRNA will be continually transcribed along a gene until enough protein is produced. Obviously, all genes are not active at the same time. The cell controls which genes are expressed at different times. Chromosomes have both structural genes that code for proteins, and regulatory sites that control gene expression.

It turns out that gene expression is not as simple as once thought. Recent discoveries have revealed many complex ways in which expression of the DNA sequence is altered.

Promoters are present upstream of the gene and are necessary for proper binding of RNA polymerase, the enzyme necessary to initiate transcription. Significant portions of the eukaryotic promoter region include the TATA box, the CAAT box, and the GC box.

Most eukaryotic genes studied also have enhancers, which greatly increase the rate of transcription. The position of the enhancer is variable, and may be brought into close contact with the promoter by proteins called transcription factors that may bend or loop the DNA into the proper position for transcription. One example is called a zinc finger.

After eukaryotic DNA is replicated, much of it is usually methylated. DNA methylation is the addition of methyl groups to cytosine nucleotides. Regions of DNA that are inactive in transcription activity are often heavily methylated. (The Y chromosome and Barr bodies (discussed below) are largely inactive in terms of gene expression, and both show a high degree of methylation.

Eukaryotic DNA is packed tightly and woven around structural proteins called histones. In order to become available for transcription, a stretch of DNA must pull away from the histones in a process termed acetylation. Loops of DNA will stretch out in order to allow transcription.

Further levels of regulation of eukaryotic gene expression include selective transport across the nuclear membrane, selective degradation of mRNA, and selective translation of mRNA. Finally, the polypeptide is further modified as it gains its native conformation of three or four levels of protein structure.

Gene expression can be controlled by steroid hormones. Steroid hormones are a special class of hormones that include the sex hormones and many hormones produced by the adrenal cortex. These hormones are small enough to enter their target cells, which they recognize by means of special receptor proteins on the surfaces of the cell membranes. Once inside the cell, a steroid hormone binds with a receptor molecule, which escorts the hormone through the nuclear membrane, and together they bind to the DNA and initiate transcription of one or more genes.

Epigenetics: the term means “on top of genetics.” In addition to the normal transcription and translation of DNA, there are processes that sometimes switch some genes on or off. Epigenetics does not change the genetic information (the DNA itself); rather, it affects the way cells express genes or shut them down.

Tags can be added to DNA itself or the histone proteins the DNA is wrapped around. Some of these tags are messages encouraging expression of the gene or preventing expression. These tags are temporary, allowing a great deal of flexibility in the messaging system responsible for determining which proteins are manufactured by a cell at a particular point in time.

Two examples of epigenetics are:

X-inactivation – Since females have two X chromosomes and males have only one (and there are very few genes on the male Y chromosome), in order for the two sexes to express the same number of genes, something called dosage compensation occurs: in each female cell, one of the X chromosomes becomes inactivated and coils up into a condensed dark structure called a Barr body. The alleles on the remaining X chromosome will be the only ones expressed in that cell.

Genetic imprinting – There are a few genes whose expression is dependent upon whether their chromosomes were passed down from the mother or the father. It is said that these genes are stamped with the memory of which parent they came from. These genes may be expressed disproportionately from either the maternal or paternal chromosome, something previously thought to be impossible.

Epigenetics is opening a whole new field of genetics, which goes beyond the DNA sequence of the genes and considers environmental effects that alter the expression of some genes.

Assignment 1 - 1 1/2 pages

Click on the link below to read about terminology used in chromosome maps.

How do geneticists indicate the location of a gene?

https://ghr.nlm.nih.gov/primer/howgeneswork/genelocation

Click on the link below and browse through the information for the 23 human chromosomes and mitochondrial DNA.

Genetics Home Reference - Chromosomes and mtDNA

https://ghr.nlm.nih.gov/chromosome

describe your chromosome using chromosome mapping terms.

Then choose a trait found on this chromosome.

summarize the information listed about this trait

Now look up your chosen trait on the following website:

Online Mendelian Inheritance in Man

http://omim.org/

describe the amount of information you found on OMIM about this trait.

Assignment 2

The case study for this module examines a set of identical twins, one of whom develops schizophrenia. The other twin is worried that she, too, will develop this psychiatric disorder. The case explains the role of epigenetics in the inheritance of this behavioral disorder.

Click on the following link to view a case study about schizophrenia: https://mylearning.suny.edu/content/enforced/1056042-2024SP-ESC-BIOL-1006_B01-11055/Content/epigenetics.pdf

Case Study - Identical Twins, Identical Fates? An Introduction to Epigenetics

Download the Case Study Report Form, fill in the answers, and submit. (Attached)

Assignment 3 - 1 1/2 pages

This assignment consists of one question. Your response should be one or two pages long. Be sure to cite any and all sources correctly so that your academic integrity is not called into question.

Copy the following question, add your answer, and submit below in one attached document.

1. Click on the links below for information about creating Health Histories and then: https://medlineplus.gov/ency/patientinstructions/000947.htm

https://www.cdc.gov/genomics/famhistory/famhist_basics.htm

· Explain the importance of Health Histories.

· Describe special circumstances that might trigger the need for these documents.

· When can issues such as race/ethnicity become important?

· Summarize the types of information that should be included. Will this differ depending upon the reason for the document?

· Is the socio-economic status of the individual important in how the health history might be used or not?

· Comment on whether you think Health Histories will become more common as our knowledge of human genomics increases.

· Creating a family health history

· Family Health History: The Basics (explore the links at the left as well)

Required readings

Lewis, R. 2018. Human Genetics, Concepts and Applications,13th ed. McGraw-Hill.

Read Chapters 9, 10, and 11 in the textbook.

Read M3 Content Guides. 1, 2, 3,

1. DNA and RNA

For a long time many scientists believed that proteins must be the hereditary molecules because they are large and complex. By the mid-1900s, however, DNA was confirmed to be the genetic molecule of heredity. Its deceptive simplicity blinded many early researchers to the fact that the key to its complexity is in the organization of its few simple nitrogenous bases.

DNA is composed of nucleotides, each containing a deoxyribose sugar (a pentagon-shaped carbon ring), a phosphate group (a phosphorus atom surrounded by four oxygens), and one of four different nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G).

Alternating sugars and phosphates form the sides of the twisted ladder-like DNA double helix. The two strands are antiparallel, which means they run in opposite directions, chemically speaking: one in a 3’-to-5’ direction and the other in a 5’-to-3’ direction (referring to the specific numbered carbons in the sugar rings).

The sugars and phosphates form the outside of the molecule. Towards the inside of the molecule, nitrogenous bases form the “rungs” of the ladder. Hydrogen bonds form between opposite nitrogenous bases (A—T, C—G): A always attaches with two hydrogen bonds to T, and C always attaches with three hydrogen bonds to G. A and G are purines, which are larger molecules than C and T, which are pyrimidines. Since each rung is always composed of one purine paired with one pyrimidine, the length of the rungs is always consistent, giving the DNA molecule stability. Single hydrogen bonds are weak, but collectively they are sufficient to hold the two complementary strands together.

DNA replication is a complex biochemical reaction involving several different enzymes responsible for initiation, elongation, and termination of the new strand, as well as mechanisms for proofreading the newly created strands, mechanisms for repairing any errors detected, and mechanisms for ligating (joining) any loose ends created. DNA replication is semiconservative. The two parent strands separate and each serves as a template for a newly synthesized strand.

Various protein enzymes carry out the following functions:

The two DNA strands begin to separate at a replication fork.

Helicases unwind and open up the helix.

DNA gyrase cuts, untwists, and reseals spots along the DNA to relax coiling tension.

An RNA primer is necessary to begin replication--it provides the first 3’ end for the first new DNA nucleotide to attach to.

DNA Polymerase elongates the chain in the 5’-to-3’ direction by adding new nucleotides.

Because the two DNA strands are antiparallel (run in opposite directions) synthesis in the 5’-to-3’ direction is continuous, but synthesis in the 3’-to-5’ direction is discontinuous. DNA nucleotides can only be added in the 5’-to-3’ direction; therefore, a continuous strand will be formed in that direction (along the leading strand). On the opposite strand (the lagging strand), numerous discontinuous short segments, called Okazaki fragments, are initiated and are created in the opposite direction. An enzyme named DNA ligase fills in the gaps between the Okazaki fragments.

RNA primers must be removed and proofreading occurs to correct errors. Polymerase enzymes can briefly “back up” in a 3’-to-5’ direction to cut out and replace an incorrect nucleotide.

RNA is a nucleic acid similar to DNA with the following differences:

RNA is usually single stranded,

The sugar in RNA is ribose, instead of deoxyribose, and

RNA contains uracil (U) instead of thymine.

RNA is manufactured along DNA in a process called transcription, which will be discussed in detail in the next content guide. Individual RNA nucleotides attach to the DNA of a gene that functions in producing a particular type of RNA. Hydrogen bonding is the same as in DNA replication (C with G, G with C, A with T), but in RNA uracil bonds with adenine (U with A).

There are three main types of RNA: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). These RNA molecules interact during the processes of transcription and translation that result in the manufacturing of proteins (protein synthesis). In addition to these three main types of RNA there are many other small forms of RNA. Research into the functions of these micro RNAs is intense right now and we are on the brink of many exciting new medical breakthroughs using these tiny molecules.

2. Making Protien

There are three main types of RNA that work together to use the information coded in the DNA to produce proteins needed by the cell:

1) Messenger RNA (mRNA) first obtains the “message” in a gene by being created along the length of the gene during transcription. Remember that the message is transferred intact because of specific base pairing. (If you are given the sequence of mRNA nucleotides, you can easily decode the sequence of DNA nucleotides in the gene).

Messenger RNA must leave the nucleus and attach to a ribosome in order to participate in the production of a particular protein. The genetic code is written in three-letter words called codons along the mRNA strand. Each codon is composed of three nucleotides that specify a particular amino acid or a termination signal.

2) Ribosomal RNA (rRNA) is transcribed along the DNA of multiple copies of genes that function to mass-produce these molecules that make up the structure of ribosomes. Ribosomes are the “protein factories” of the cell, and are extremely numerous. Ribosomal RNA is the largest type of RNA molecule, and produces two subunits, one large and one small, which remain apart until they combine in order to produce proteins by associating with mRNA and tRNA.

3) Transfer RNA (tRNA) is the smallest RNA molecule. Its function is to transport amino acids to the ribosome, where they are inserted into the correct position in the growing polypeptide chain of amino acids being produced. Transfer RNA molecules must therefore have one end that attaches to a specific amino acid (the amino acid binding site) and another end that attaches to the codon on the mRNA molecule (the anticodon loop). The anticodon on the tRNA molecule is composed of three nucleotides that are complementary to a particular codon on the mRNA strand.

Now, let’s go over the steps involved in manufacturing a protein from directions contained within the genetic code of the DNA of a gene:

Transcription is the first part of the process. An mRNA strand will be created along the DNA template strand through transcription: the DNA helix unwinds and its two strands separate to allow access to the gene on the template strand; then RNA polymerase catalyzes the sequential attachment of new complementary RNA nucleotides, creating the mRNA strand that now contains the genetic code from this gene.

In a eukaryotic cell, once the mRNA molecule is finished transcribing the gene and detaches from the DNA it must move out of the nucleus through the double nuclear membrane to a ribosome in the cytoplasm. The RNA is termed pre-mRNA when it is released from the DNA, because it needs to undergo further processing before it is ready to translate a protein at the ribosome.

Posttranscriptional RNA processing includes the addition of a 7mG cap to the 5’ end and the addition of a poly-A tail to the 3’ end (the cap and tail seem to protect the mRNA from being degraded, and they may assist the mRNA through the nuclear membrane). Splicing is the next step. Introns are intervening sequences that are not used to translate the protein and must be removed before the mRNA attaches to the ribosome. Exons are the stretches of mRNA that will be expressed and translate the protein at the ribosome. Alternative splicing may explain why the sequencing of the human genome revealed far fewer genes than were expected (about 30,000). Many of our genes are capable of producing several different proteins each, depending on how they are spliced. This may also partially explain the function of some introns (they may be necessary for some proteins, but not for others).

An mRNA molecule will be available to translate proteins for a few hours before being degraded by the cell. If the cell continues to need the protein product, more mRNA will be transcribed from the DNA. If the protein is no longer needed, no metabolically expensive excess will be produced.

Translation: the production of proteins from directions on an mRNA strand that transcribed this information from a gene (a stretch of DNA along a chromosome) is termed translation because the language of nucleic acids (sequences of nucleotides) is translated to the language of proteins (sequences of amino acids). Translation occurs on individual ribosomes, where large ribosomal subunits combine with small ribosomal subunits, forming “workbenches” for the manufacture of proteins. At each ribosome, codons along the mRNA can temporarily attach to anticodons of tRNA molecules that bring specific amino acids to the ribosomal complex. The sequence of amino acids that are hooked together by peptide bonds follows the sequence of nucleotides along the mRNA strand, which carries the genetic code from the DNA of the gene. Codons (triplet code words) on the mRNA will determine the sequence of amino acids ultimately linked together at a ribosome to create the protein chain.

3.Gene Expression and Epigenetics

The fact that mRNA has a short lifespan is important in giving the cell precise control over the amount of each protein that is transcribed at any one time. If only a small amount is needed, no more mRNA will be transcribed along the gene. If more protein is required, mRNA will be continually transcribed along a gene until enough protein is produced. Obviously, all genes are not active at the same time. The cell controls which genes are expressed at different times. Chromosomes have both structural genes that code for proteins, and regulatory sites that control gene expression.

It turns out that gene expression is not as simple as once thought. Recent discoveries have revealed many complex ways in which expression of the DNA sequence is altered.

Promoters are present upstream of the gene and are necessary for proper binding of RNA polymerase, the enzyme necessary to initiate transcription. Significant portions of the eukaryotic promoter region include the TATA box, the CAAT box, and the GC box.

Most eukaryotic genes studied also have enhancers, which greatly increase the rate of transcription. The position of the enhancer is variable, and may be brought into close contact with the promoter by proteins called transcription factors that may bend or loop the DNA into the proper position for transcription. One example is called a zinc finger.

After eukaryotic DNA is replicated, much of it is usually methylated. DNA methylation is the addition of methyl groups to cytosine nucleotides. Regions of DNA that are inactive in transcription activity are often heavily methylated. (The Y chromosome and Barr bodies (discussed below) are largely inactive in terms of gene expression, and both show a high degree of methylation.

Eukaryotic DNA is packed tightly and woven around structural proteins called histones. In order to become available for transcription, a stretch of DNA must pull away from the histones in a process termed acetylation. Loops of DNA will stretch out in order to allow transcription.

Further levels of regulation of eukaryotic gene expression include selective transport across the nuclear membrane, selective degradation of mRNA, and selective translation of mRNA. Finally, the polypeptide is further modified as it gains its native conformation of three or four levels of protein structure.

Gene expression can be controlled by steroid hormones. Steroid hormones are a special class of hormones that include the sex hormones and many hormones produced by the adrenal cortex. These hormones are small enough to enter their target cells, which they recognize by means of special receptor proteins on the surfaces of the cell membranes. Once inside the cell, a steroid hormone binds with a receptor molecule, which escorts the hormone through the nuclear membrane, and together they bind to the DNA and initiate transcription of one or more genes.

Epigenetics: the term means “on top of genetics.” In addition to the normal transcription and translation of DNA, there are processes that sometimes switch some genes on or off. Epigenetics does not change the genetic information (the DNA itself); rather, it affects the way cells express genes or shut them down.

Tags can be added to DNA itself or the histone proteins the DNA is wrapped around. Some of these tags are messages encouraging expression of the gene or preventing expression. These tags are temporary, allowing a great deal of flexibility in the messaging system responsible for determining which proteins are manufactured by a cell at a particular point in time.

Two examples of epigenetics are:

X-inactivation – Since females have two X chromosomes and males have only one (and there are very few genes on the male Y chromosome), in order for the two sexes to express the same number of genes, something called dosage compensation occurs: in each female cell, one of the X chromosomes becomes inactivated and coils up into a condensed dark structure called a Barr body. The alleles on the remaining X chromosome will be the only ones expressed in that cell.

Genetic imprinting – There are a few genes whose expression is dependent upon whether their chromosomes were passed down from the mother or the father. It is said that these genes are stamped with the memory of which parent they came from. These genes may be expressed disproportionately from either the maternal or paternal chromosome, something previously thought to be impossible.

Epigenetics is opening a whole new field of genetics, which goes beyond the DNA sequence of the genes and considers environmental effects that alter the expression of some genes.

Assignment 1 - 1 1/2 pages

Click on the link below to read about terminology used in chromosome maps.

How do geneticists indicate the location of a gene?

https://ghr.nlm.nih.gov/primer/howgeneswork/genelocation

Click on the link below and browse through the information for the 23 human chromosomes and mitochondrial DNA.

Genetics Home Reference - Chromosomes and mtDNA

https://ghr.nlm.nih.gov/chromosome

describe your chromosome using chromosome mapping terms.

Then choose a trait found on this chromosome.

summarize the information listed about this trait

Now look up your chosen trait on the following website:

Online Mendelian Inheritance in Man

http://omim.org/

describe the amount of information you found on OMIM about this trait.

Assignment 2

The case study for this module examines a set of identical twins, one of whom develops schizophrenia. The other twin is worried that she, too, will develop this psychiatric disorder. The case explains the role of epigenetics in the inheritance of this behavioral disorder.

Click on the following link to view a case study about schizophrenia: https://mylearning.suny.edu/content/enforced/1056042-2024SP-ESC-BIOL-1006_B01-11055/Content/epigenetics.pdf

Case Study - Identical Twins, Identical Fates? An Introduction to Epigenetics

Download the Case Study Report Form, fill in the answers, and submit. (Attached)

Assignment 3 - 1 1/2 pages

This assignment consists of one question. Your response should be one or two pages long. Be sure to cite any and all sources correctly so that your academic integrity is not called into question.

Copy the following question, add your answer, and submit below in one attached document.

1. Click on the links below for information about creating Health Histories and then: https://medlineplus.gov/ency/patientinstructions/000947.htm

https://www.cdc.gov/genomics/famhistory/famhist_basics.htm

· Explain the importance of Health Histories.

· Describe special circumstances that might trigger the need for these documents.

· When can issues such as race/ethnicity become important?

· Summarize the types of information that should be included. Will this differ depending upon the reason for the document?

· Is the socio-economic status of the individual important in how the health history might be used or not?

· Comment on whether you think Health Histories will become more common as our knowledge of human genomics increases.

· Creating a family health history

· Family Health History: The Basics (explore the links at the left as well)