Lecture 1

Question 1

Outline some of the ways in which genetics is important to us all

Answer 1

• appearance
• susceptibility to diseases and disorders
• research and techniques to diagnose and treat hereditary
• intelligence, personality
• GMO crops
• mass-produce pharmaceuticals and other commercial products

Question 2

Give at three example of the role of genetics in society today

Answer 2

• role in diagnosis and treatment of hereditary diseases
• breeding plants and animals for improved production and disease resistance
• producing pharmaceuticals and novel crops through genetic engineering

Question 3

Explain why genetics is crucial to modern biology

Answer 3

• provides unifying principles:
• • genetic code is universal (all organisms use nucleic acid as their genetic material)
• • all organisms encode genetic information in the same manner
• the study of many other biology disciplines (like dev bio, ecology, evo bio) is supported by genetics

Question 4

List the three traditional subdisciplines of genetics and summarize what each covers

Answer 4

1. TRANSMISSION genetics
   - - inheritance of genes from one generation to the next
   - -location of genes on chromosomes and gene mapping
2. MOLECULAR genetics
   - -structure, organization, and function of genes at the molecular level
   - -processes by which gen info transferred and expressed
3. POPULATION genetics
   - -genetic variation and changes in genes and allele frequencies within groups of individuals of the same species over time

Question 5

Indicate which of the three subdisciplines of genetics the following focuses on.

Analysis of pedigrees to determine the probability of someone inheriting a trait

Answer 5

Transmission genetics

Question 6

Indicate which of the three subdisciplines of genetics the following focuses on.

Study of people on a small island to determine why a genetic form of asthma is prevalent on the island

Answer 6

population genetics

Question 7

Indicate which of the three subdisciplines of genetics the following focuses on.

Effect of nonrandom mating on the distribution of genotypes among a group of animals

Answer 7

population genetics

Question 8

Indicate which of the three subdisciplines of genetics the following focuses on.

Examination of the nucleotide sequences found at the chromosome ends

Answer 8

Molecular genetics

Question 9

Indicate which of the three subdisciplines of genetics the following focuses on.

Mechanisms that ensure a high degree of accuracy in DNA replication

Answer 9

Molecular genetics

Question 10

Indicate which of the three subdisciplines of genetics the following focuses on.

Study of how the inheritance of traits encoded by genes on sex chromosomes (sex-linked traits) differs from the inheritance of traits encoded by genes on nonsex chromosomes (autosomal traits)

Answer 10

transmission genetics

Question 11

Describe some of the ways in which your own genetic makeup affects you as a person. Be as specific as you can

Answer 11

• physical appearance (hair color, eye color, height, build, complexion), and maybe relate it to a relative
• susceptibility to diseases that run in the family

Question 12

Compare and contrast Eukaryotic and prokaryotic cells

Answer 12

Both:

• lipid bilayer membranes
• DNA genomes
• machinery for DNA replication, transcription, translation, energy metabolism, response to stimuli, growth, and reproduction

Prokaryotes:

• no nucleus
• haploid
• usually sincle circular chromosome with 1 origin of rep
• single chromosome is replicated with each copy moving to opposite sides of cell
• no histones

Eukaryotes:

• nucleus
• diploid common
• usually mult linear chromosomes (containing centromeres, telomeres, adn mult origins of replication
• chromosomes replicated and segregate during mitosis/meiosis to proper location
• histones

Question 13

Compare and contrast gametes and somatic cells

Answer 13

Both:
- contain DNA

Gametes only:

• nucleus unites with another cell to form a new organism
• haploid
• divides by meiosis
• in mammals, they are egg and sperm

Somatic only:

• form body of organism
• any cell that’s not a gamete

Question 14

Compare and contrast nuclear versus mitochondrial DNA

Answer 14

Both:

• double-stranded
• contains genes

Nuclear:

• linear
• contained within nuclear membrane
• two copies per somatic cell
• inherited equally from both parents
• 20,000 to 25,000 genes

Mitochondrial:

• circular
• not within a nuclear membrane
• multiple copies within the mito
• only 37 genes
• solely inherited from the mother

Question 15

Compare and contrast gene and allele

Answer 15

Gene:

• basic unit of heredity
• dictated by nucleotide sequence
• usually encodes functional RNA or polypeptide

Allele: variant form of a gene, arising through mutation

Question 16

Compare and contrast DNA and chromosome

Answer 16

Chromosome = structure of DNA and associated protein

Nucleotide sequence of DNA contains genetic info

Question 17

Should a person’s genetic makeup be used in determining his or her eligibility for life insurance? Pros and cons

Answer 17

Pros:

• genetic susceptibility to stuff is relevant info regarding consequences of exposure to certain occupational hazards.
• Genes that result in neurodegenerative diseases, breast cancer, etc could be considered preexisting conditions
• –insurance companies have a right to exclude people with preconditions so insurance rates can be lower for general pop

Cons:

• purpose of insurance is to spread risk and pool assets
• • excluding people based on genetics excludes those who need insurance most. Eventually, as more diseases are linked to genes, almost no one will be insurable
• many genes are “incompletely penetrant” and variably expressed; just because you have the gene doesn’t mean you’ll get the disease. And you might get it without the gene.

Question 18

Should biotechnology companies be able to patent newly sequenced genes? Pros and cons

Answer 18

Pros:

• provides companies with protection for their investment in r & d of new drugs and therapies
• – without, less incentive to spend lots of $$ in gen research, slowing pace of advancement in med research

cons:
- how can company patent something every person has? Like patenting an arm

Question 19

Should gene therapy be used on people? Pros and cons

Answer 19

Pros:
-cure previously incurable or intractable gen disorders

Cons:

• may lead to gen engineering of people for bad intentions
• – who determines what is a genetic defect?

Question 20

Should genetic testing be made available for inherited disorders for which there’s no cure or treatment? Pros and cons

Answer 20

Pros:

• relief from unnecessary anxiety of test is neg
• if test positive, gives time to prepare (how to spend one’s life, decisions about whether to have children, avoid risk factors)
• info about one’s makeup is a right; it’s that person’s choice to see it or not

Cons:

• positive result like receiving death sentence
• foster feelings of hopelessness and depression, possibly culminating in suicide
• could foster discrimination from employers, society at large, insurance companies

Question 21

What are the two basic cell (structurally) and how do they differ

Answer 21

Prokaryotic and eukaryotic cells

Prokaryotes: no membrane- bound organelles or a true nucleus (Eukaryotes have both). Chromosome(s) instead within cytoplasm.

Question 22

A cell has circular chromosome and no nuclear membrane. Its DNA is complexed with some histone proteins. Is this cell from a bacterium, an archean, or a eukaryote? Explain.

Answer 22

Archaea

Not euk b/c lacks nuclear mem and has single circular chromosome

Not bac b/c hsitones

Question 23

Compare and contrast prok and euk chromosomes

Answer 23

Prokaryotic chromosome:

• contains entire genome
• smaller
• one origin of replication
• condensed into nucleoids (loops of DNA compacted into dense body)

Eukaryotic chromosome:

• contains portion of genome
• larger
• multiple origins of replication
• DNA packaged into nucleosomes, which are coiled and packaged into higher order structures

Question 24

Name three essential structural elements of a functional eukaryotic chromosome and describe their functions

Answer 24

1. Centromere
   - point of attachment for kinetochore where spindle fibers attach
2. Telomeres
   - natural ends of linear eukaryotic chromosomes
   - stabilize end of chromosome
   - possible role in limiting cell division
3. Origins of replication
   - starting points for DNA synthesis (replication)

Question 25

Sketch and identify the four different types of chromosomes based on the position of the centromere.

Answer 25

small arm is p (for petite), big arm is q Metacentric: centromere is centered on chromosome; p and q equal in length ------+------ submetacentric: centromere just a bit off center; p just a bit shorter than q - ------+----- acrocentric: centromere very off center, but not on very end of chromosome - ---------+-- telocentric: centromere is on very end of chromosome - -----------+

Question 26

What is the endosymbiotic theory? How does it help to explain some of the characteristics of mitochondria and chloroplasts?

Answer 26

proposes that mito and chloro evolved from formerly free-living bac that became endosymbionts within larger eukaryotic cell. - Chloro and mito contain genomes encoding for proteins, tRNAs, and rRNAs - genome sizes, circular chromosome structure, and other aspects of genome structure similar to eubac cells - chloro and mito ribosomes similar in size and function to eubac ribosomes. - DNA seq in mito and chloro genomes are most similar to those of eubac.

Question 27

A chromosome consists of two sister chromatids. Does the genetic info on the two sister chromatids come from only one parent or from both?

Answer 27

Only one parent. Prior to mitosis the DDNA is replicated so that there are two sister chromatids per chromosome. These two sister chromatids will separate during mitosis resulting in one chromosome (chromatid) from each parent in the resulting embryo

Question 28

The Out of Africa hypotiesis (also called the African Replacement hypothesis) proposes that Homo sapiens arose in Africa and evolved there for several hundred thousand years. Then, some 85,000 years ago, a small band of Homo sapiens migrated out of Africa and populated the remainder of the world. Based on this hypothesis, what predictions would you make about worldwide human variation in mtDNA?

Answer 28

1. most variation in human mtDNA will be found within Africa because human groups there have a longer evolutionary history and have had time to develop genetic differences 2. Human populations outside of Africa will have very similar mtDNA because they are derived from a small group that carried only a subset of the mtDNA variation found in Africa. Because the founding event occurred relatively recently (evolutionarily) there has been little time for genetic differences to accumulate outside of Africa

Question 29

Waht are some possible social and ethical issues associted with mitochondrial replacement therapy (MRT)? Present arguments for and against approving MRT for the prevention of the births of children with mitochondrial disorders

Answer 29

Mitochondrial replacement theory has been approved for preventing mitochondrial disorders in the UK, but its use in the US is still under consideration possible issues: - inclusion of gen material from 3 people in conception of a child raises issues of parental rights. Would the cytoplasm donor have the same parental rights as the nuclear mother and father? - Would a 3-parent child have legal right of inheritance from cytoplasm donor, similar to rights of nuclear children? Would it equal that of nuclear children? - Is the procedure safe? Could combining DNA from 3 sources lead to developmental problems? What about about problem that manifested in adulthood? - Is conceiving a child through MRT creating something unnatural? Is this playing God? - Who has the right to decide if MRT should be allowed? Should society have a role or is this a decision to be made strictly by the parents? Does the individual conceived by MRT have any rights in this question?