EXAM 1: Ch1-5

Question 1

1. Some people believe that SARS CoV-2 originated in a lab. What are three compelling genetic reasons why this is very unlikely to be the case?

Answer 1

1. Closely related to a bat
2. wild virus 96% match)
3. If it was created, it would reveal a genetic backbone.

Question 2

What does it mean to say that viruses undergo recombination?

Answer 2

Usually we think of recombination as something that occurs in meiosis (Chapter 2). But it can also occur in haploid cells like bacteria as well as viruses. In this case, it occurs when viruses that are distinct somehow come into close proximity (probably by coinfecting the same cell) and each ends up contributing part of their genome to new virus—a virus with a genome that is a new combination of genomic regions from the parental strains.

Question 3

Using the concept of a molecular clock, how long ago did Boni et al. estimate that SARS 1 and SARS CoV-2 diverge?

Answer 3

The point estimate is around 1200 (800 years ago, but the confidence interval is wide and extends to 1600, or 400 years ago).

Question 4

In biology, what do we call one of these branching figures with species or samples at the tips?

Answer 4

A phylogeny or a phylogenetic tree.

Question 5

Are species (or samples) that are separated by short branches closely related or distantly related?

Answer 5

Extant species are at the tips of such a tree. You trace branches back to find forks, or nodes. These represent the common ancestor between the descendent species. How long the branches are you must trace back to find this common ancestor tells you how much genetic evolution separates the extant species. The answer to the question should be clear from what I’ve written.

Question 6

What is molecular epidemiology? What is a superspreader event?

Answer 6

A superspreasder event is where many people become infected at the same time and place—either because someone is transmitting a lot of virus (highly infectious), because the conditions are perfect (e.g. indoors for a prolonged period of time without mask wearing), or, most often, both.

Question 7

example, did scientists use air traffic data and contact tracing to know how the virus spread? Or is there something in the virus itself that records the pattern of how it spreads and, if so, what?

Answer 7

Mutations accumulate as viruses are transmitted from one host to the next. Because new mutations hardly ever overwrite (or reverse) previous mutations (at least on the short time scales we are talking about here), it means that the mutations contain a record of transmission patterns across time and space.

Question 8

10. Vaccines: What protein are the leading vaccines using as their target for eliciting an immune response? Why this protein and not others from SARS CoV-2?

Answer 8

Because this protein is the major target of our adaptive immune system when the virus infects our body.

Question 9

Molecular Epidemiology

Answer 9

Using geniomic sequencing and modeling to infer the spread, dynamics of infectious diseases

Question 10

Pseudotype

Answer 10

Unrelated virus with SARS protein
Switching D (aspertate) for G (glycine) ever so slightly tweaks the spike protein

Question 11

How would covid vaccine work @ a genetic level

Answer 11

focuss on th spike protein because we build antibodies on spike proteins (inject genetic info of spike protein into cells)

Question 12

How can we make a tree describing the relationship of all living things when living things are some mind-blowingly different from each other? In other words, what feature do all living things share that we can use to build a tree?

Answer 12

all living things on Earth can trace their descent back to a common ancestor. … Then, we can use the shared derived traits to organize the species into

Question 13

What are the major phylogenetic domains of all cellular organisms?

Answer 13

The three domains are the Archaea, the Bacteria, and the Eukarya

Question 14

What domain of the biological world is not cellular and not readily comparable to cellular organisms?

Answer 14

Viruses

Question 15

Which of the phylogenetic domains are the prokaryotes?

Answer 15

eubacteria and archaebacteria

Question 16

What is the major differences between prokaryotes and eukaryotes?

Answer 16

eukaryotic cells have a distinct nucleus containing the cell’s genetic material, while prokaryotic cells don’t have a nucleus and have free-floating genetic material instead

Question 17

T or F: all prokaryotes are more closely related to each other than they are to eukaryotes.

Answer 17

F

Question 18

What are the three major divisions of genetics?

Answer 18

transmission genetics, molecular genetics, and population genetics

Question 19

Why, in genetics, are we so obsessed with tracking chromosomes in mitosis and meiosis?

Answer 19

Although mitosis and meiosis both involve cell division, they transmit genetic material

Question 20

What’s it mean to say that a cell is diploid? What does it mean to say it’s haploid?

Answer 20

Haploid” refers to any cell that has 23 chromosomes (half of the total 46). “Gametes” are specifically sex cells that have 23 chromosomes. “Diploid” refers to any cell that has all 46 chromosomes

Question 21

Sars COV 2 orgin in bats is what division of genetics

Answer 21

Population

Question 22

Bedfords discovery of transmission is what division of genetics

Answer 22

Transmission and population

Question 23

D614G affects hydrogen bond is what division of genetics

Answer 23

Molecular

Question 24

Karyotype

Answer 24

complete set of the chromosomes

Question 25

T/F Archea is closer related to Eukaryotes than to bacteria

Answer 25

True

Question 26

In mitosis, what are lined up alont the center and then pulled apart?

Answer 26

Sister Chromatids

Question 27

What happens during meisosi 1 +2?

Answer 27

1: homologues are lined up and then pulled apart 2: sister chromatids are lined up then pulled apart

Question 28

Crossing over, when does it occur?

Answer 28

prophase of meiosis 1

Question 29

when does assortment occur?

Answer 29

Metaphase 1 and anaphase 1

Question 30

If a species has n chromosomes how many ways can it be shuffled?

Answer 30

2^n, alot of genetic variation without crososing over

Question 31

How are bacteria different from both archea and eukaryotes?

Answer 31

bacteria have no histones associated with their chromosomes and the other two groups do

Question 32

In which stage of the cell cycle does the cell duplicate its DNA?

Answer 32

S phase

Question 33

Eukaryotic cells that contain more than two sets of genetic information are referred to as...

Answer 33

polyploid

Question 34

Function of the telomere?

Answer 34

to protect the end of the DNA molecule

Question 35

What is the constricted region of the chromosome where the kinetochore forms

Answer 35

centromere

Question 36

The products of mitosis normally are

Answer 36

genetically identical to the parent cell

Question 37

What stage of mitosis involves sister chromatids separating and moving toward opposite poles?

Answer 37

anaphase

Question 38

In order to pass the G2/ M checkpoint the cell must have

Answer 38

DNA replicated and undamaged

Question 39

A cell has 6 chromosomes while in G1 stage. How many chromosomes and how many DNA molecules will it have in G2?

Answer 39

6 chromosomes and 12 DNA molecules

Question 40

In which stage of meiosis does the separation of homologous chromosomes occur?

Answer 40

Anaphase 1

Question 41

One source of genetic variation is the random distribution materna and paternal chromosomes, the other is ....

Answer 41

crossing over at prophase 1

Question 42

Which statement is not a difference between meiosis and mitosis

Answer 42

sister chromatids seperate during mitosis but not meiosis | - separate in mitosis and 2nd division of meiosis

Question 43

How many ova, plural ovum, can be produced from two primary oocytes through meiosis?

Answer 43

two

Question 44

the two proceeses that can create genetic differences

Answer 44

independent assortment and crossing over

Question 45

What is n in 2^n?

Answer 45

n represents the number of homologous chromosome paris per cell entering meiosis

Question 46

crossing over shuffles alleles on

Answer 46

non sister chromatids of homologous chromosomes

Question 47

Transmission genetics

Answer 47

how genes are passed from parents to offspring

Question 48

Population genetics

Answer 48

how organisms that share genes (populations) change over time

Question 49

Molecular genetics

Answer 49

molecular details of how genetic information is stored, replicated and processed

Question 50

alleles

Answer 50

different versions of a gene

Question 51

S phase

Answer 51

DNA duplicates

Question 52

M phase

Answer 52

nuclear and cell division

Question 53

Where do microtubules attatch?

Answer 53

kinetochore

Question 54

Mitosis

Answer 54

sister chromatids seperate and move toward opposite poles | chromosomes line up on the metaphase plate

Question 55

Meiosis

Answer 55

gametes are produced that carry half the normal # of chromosomes

Question 56

Fertilization

Answer 56

two haploid gametes fuse and restore to diploid

Question 57

Heterozygote

Answer 57

2 different alleles

Question 58

Homozygote

Answer 58

2 copies of same alele

Question 59

The principle of segregation

Answer 59

each individual diploid organism posseses two alleles for any particular characteristic. These two alleles segregate when gametes are formed and one allele goes into each game. the alleles segregate in equal proportions during meiosis.

Question 60

Independent vs mutually exclusive

Answer 60

``` Independent= x ME= + ```

Question 61

heterogametic

Answer 61

males XY

Question 62

homogametic

Answer 62

females XX

Question 63

Do all chromosomes benefit from recombination?

Answer 63

Not the Y chromosomes

Question 64

SRY

Answer 64

a trasncription factor. Expressed or not expressed | protein that binds DNA near specific genes to turn then on.

Question 65

Nondisjunction

Answer 65

when chromosomes dont segregate properly in meiosis. Various possibilities exhist

Question 66

Which karotype is lethal?

Answer 66

YO- can live without a Y but cannot live without an X

Question 67

Chromosomal mosacisim

Answer 67

Cell missing chromosome

Question 68

Phenotypes

Answer 68

1. Femalese are diploid (XX) recessive alleles are masked in heterozygotes. Males are haploid (X) recessive are unmasked

Question 69

Autosomal phenotypes

Answer 69

everyone is diploid= recessive are masked in the heterozygotes, unmasked in homozygotes

Question 70

Heredity

Answer 70

daughters always get their fathers X and a random one of their mothers two X's/ sons get no X from their fathers (they get a Y) and they get a random one of mothers two Xs

Question 71

Disappearing

Answer 71

affected fathers pass it to 100% of their daughters since usually the mother is a non-carrier, the daughters will be carriers

Question 72

Reappearing

Answer 72

When the daughters grow up and have children, 1/2 of their sons will be affected

Question 73

Dosage Compensation

Answer 73

Mechanisms to deal with unequal # of chromosomes 1. doubled expression of genes on X in XY/XX 2. inactive all but 1 X chromosomes

Question 74

Incomplete Dominance

Answer 74

when the heterozygote has a phenotype intermediate between the two homozygotes 1:2:1

Question 75

Complete Dominance

Answer 75

when the heterozygote phenotype matches the homozygote dominant 3:1

Question 76

Codominace

Answer 76

both traits are shown | patchy color

Question 77

blood types

Answer 77

AB can get any blood | O is universal donor

Question 78

Epistasis

Answer 78

when the gynotype at one gene masks the genotype another | - antigen cannot be added

Question 79

Epistatic

Answer 79

gene that does the masking

Question 80

hypostatic

Answer 80

gene that gets masked

Question 81

example of recessive epistasis

Answer 81

Labrador retriever color | anything with ee is yellow

Question 82

Dominant epistasis

Answer 82

a dominant allele at one locus masks the effect of another locus

Question 83

9:3:3:1 ?

Answer 83

dihybrid cross, two independent loci

Question 84

With genetic sex-determination mechanism, what is true?

Answer 84

Sex is determined by genes on undifferentiated chromosomes

Question 85

What did Mary Lyon propose about sex chromosomes in mammals?

Answer 85

One X chromosome in each female cell becomes inactivated, and the process of selection is random

Question 86

A human male has XXXXXY would contain how many barr bodies?

Answer 86

2

Question 87

In the evolution of a Y chromosome in mammalia, what can be assumed?

Answer 87

it evolved from an autosome

Question 88

A mutant human gene will be inherited by

Answer 88

all of the sons but none of the daughters

Question 89

model genetic organisms

Answer 89

organisms that are widely used in genetic research and can serve as models for genetic systems

Question 90

Barr Bodies

Answer 90

dark staining bodies in the nuclei of cells from female cats discovered by Murray Barr an inactive X chromosome

Question 91

Lethal Alleles

Answer 91

2:1 ratio

Question 92

F2 phenotypic ratio duplicate recessive

Answer 92

9:7

Question 93

F2 dominant epistasis

Answer 93

12:3:1

Question 94

F2 recessive epistasis

Answer 94

9:3:4

Question 95

A _____ allele causes death at an early stage, often before birth and, therefore, some genotypes do not appear in the progeny.

Answer 95

lethal

Question 96

Why does gene interaction often arise when different loci influence different steps in a common biochemical pathway?

Answer 96

the product of one enzyme affects the substrate of another

Question 97

Anticipation is the

Answer 97

stronger or earlier expression of a trait as it is passed from generation to generation.

Question 98

In the human ABO blood type system, which of the following outcomes is NOT expected to occur?

Answer 98

an AB child from a mating of an A individual and an O individual

Question 99

True or False? It is possible to see gene interaction at multiple loci.

Answer 99

True

Question 100

True or False? A father that is heterozygous for precocious puberty, a sex-limited characteristic, has a 50% chance of passing on the allele to his child, regardless of the child's sex.

Answer 100

True

Question 101

Characteristics that have a few easily distinguished phenotypes are called _____ characteristics.

Answer 101

discontinuous

Question 102

A phenotype produced by an environmental effect that mimics a phenotype produced by a genotype is called a

Answer 102

phenocopy

Question 103

A 13:3 ratio is produced by

Answer 103

gene interaction