Genes

Question 1

Population genetics

Answer 1

Study of the gene pool of a population over time

Question 2

Molecular genetics

Answer 2

Study of the molecular structure and function of genes

Question 3

Cell cycle

Answer 3

Period between birth of a cell & its division into 2 daughter cells.

Question 4

Prophase early

Answer 4

Mitotic spindles form from centrosomes

Chromosomes condense

Question 5

Prophase later

Answer 5

Nuclear envelope breaks down

Chromosomes attach to mitotic spindle

Question 6

Metaphase

Answer 6

Chromosomes line up at equator

Sisters chromatids attached to opposite poles of mitotic spindle

Question 7

Anaphase

Answer 7

• Cohesion between sister chromatids lost

- Chromatids segregate to opposite poles, driven by shortening microtubules

Question 8

Telophase

Answer 8

• Chromosomes decondense
• Nuclear envelope reforms
• Cytokinesis begins

Question 9

Meiosis I

Answer 9

• Divides chromosome pair
• REductional division
• 2 haploid daughter cells

Question 10

Meiosis II

Answer 10

• Divides sister chromatids
• Equational division
• 4 haploid gametes

Question 11

Prophase I

Answer 11

• Chromosomes condense
• Synapsis of homologous chromosomes
• Crossing over occurs

Question 12

Metaphase I

Answer 12

• Homologous chromosome pairs line up at equator

Question 13

Anaphase I

Answer 13

• Homologous chromosomes separate to opposite poles

Question 14

Telophase I

Answer 14

• Each pole has one original homologous chromosome
• Each chromosome still consists of two chromatids
• Cytokinesis completes meiosis I

Question 15

At which stage of meiosis are homologous chromosomes separated?

Answer 15

Anaphase I

Question 16

In humans, how many bivalents can be seen at prophase I of meiosis?

Answer 16

23

bivalents = haploid number

Question 17

Mice have a diploid chromosome number of 40. How many chromatids are present at each cell at metaphase II of meiosis?

Answer 17

40 chromatids

Question 18

Penetrance

Answer 18

Measure of the percentage of individuals with a given genotype who exhibit the expected phenotype

Question 19

Why is the domantic white W allele epistatic to all other coat colour genes?

Answer 19

Dominant, LOF mutation in c-kit, is required for proliferation + migration of melanocytes

Question 20

c-kit

Answer 20

Transmembrane growth factor receptor for tyrosine kinase protein

Question 21

Expressivity

Answer 21

measure of the extent to which a given genotype is expressed at the phenotypic level

Question 22

Transposable element

Answer 22

Piece of DNA which can move about the genome

Question 23

Allelic variation

Answer 23

Alleles may vary in severity of phenotypes they cause, e.g. cystic fibrosis

Question 24

How does the SRY gene confer maleness?

Answer 24

Transcription factor used to regulate gene expression necessary for testes formation.

Question 25

Barr body

Answer 25

Inactivated condensed form of second X chromosome present in females.

Question 26

True/False? | A linkage map is based on recombination frequencies

Answer 26

True

Question 27

T/F? | Linked alleles stay together at meiosis

Answer 27

True

Question 28

T/F? | Unlinked genes undergo independent assortment at meiosis

Answer 28

True

Question 29

T/F? | Crossing over never occurs between linked genes

Answer 29

False

Question 30

Endosymbiotic theory explains the presence of what structures in eukaryotic cells?

Answer 30

Mitochondria and chloroplasts

Question 31

Most common type of DNA polymorphism in the human genome is

Answer 31

SNP's

Question 32

Types of aneuploidy

Answer 32

Nullisomy Monosomy Trisomy Tetrasomy

Question 33

Nullisomy

Answer 33

Loss of pair of homologous chromosomes (2n-2) | No viable birth in humans

Question 34

Monosomy

Answer 34

Loss of single chromosome (2n-1)

Question 35

Trisomy

Answer 35

One extra chromosome (2n+1)

Question 36

Tetrasomy

Answer 36

An extra pair of chromosomes (2n+2)

Question 37

How does anueploidy arise?

Answer 37

Non disjunction during meiosis

Question 38

Down syndome

Answer 38

Trisomy 21 or Robertsonian translocation Genetic mosaicism

Question 39

Patau syndrome

Answer 39

Trisomy 13

Question 40

Edwards syndrome

Answer 40

Trisome 18

Question 41

Robertsonian translocation

Answer 41

Can cause down syndrome | Translocation of chromosome 21 and 14

Question 42

Disorders resulting from monosomy of sex chromosomes

Answer 42

Turner's syndrome, XO (45, X)

Question 43

Disorders resulting from trisomy of sex chromosomes

Answer 43

``` Klinefelter syndrome (47, XXY) Triplo-X (47, XXX) XXY syndrome (47, XXY) ```

Question 44

Considering chromosome inactivation, why is phenotype still expressed in aneuploidy individuals?

Answer 44

Not all genes on inactive X are switched off, genes in PAR shared by X and Y arent inactivated causing greater expression.

Question 45

Pseudoautosomal region

Answer 45

Small terminal region of homologous sequences on X and Y chromosomes which pair and recombine during meiosis.

Question 46

High heritability means genetic determination. | True/False?

Answer 46

FALSE | e.g. height has increased over the population in the past 100 years, NS wont act that quickly, due to lifestyle changes

Question 47

Differences between groups for traits with high heritability are the result of genetic differences. True/False?

Answer 47

FALSE | e.g. difference in IQ found between African Americans and White Americans isn't necessarily due to genetic differences

Question 48

Kinetochore

Answer 48

mutiprotein complex that assembles at the centromere of a chromosome and is the site where microtubules attach

Question 49

Karyotype

Answer 49

set of chromosomes in an individual

Question 50

SRY gene

Answer 50

COnfers maleness in mammals

Question 51

Non disjunction

Answer 51

Failure of chromosomes or sister chromatids to separate properly during meiosis

Question 52

Synapsis

Answer 52

pairing of two homologous chromosomes

Question 53

Variable expressivity

Answer 53

When individuals w/ the same genetic mutation show different levels of expression of the phenotype. Can be due to effects of modifier genes that differ between individuals, or due to environmental effects.

Question 54

Endosymbiont theory

Answer 54

Hypothesis that mitochondria and chloroplasts originated as free-living prokaryotes that invaded a primitive eukaryotic cell

Question 55

cambrian explosion

Answer 55

500 mil years ago

Question 56

Fitness is

Answer 56

Measured by the number of surviving offspring produced by individuals of a specific genotype. Average reproductive success of individuals with a specific genotype

Question 57

position cloning

Answer 57

Molecular cloning of a gene on the basis of its position on the chromosome

Question 58

recombinant type individual

Answer 58

Individual that has a non-parental combination of genetic markers as the result of crossing-over or independent assortme

Question 59

Pleiotropic

Answer 59

Genes or mutations that affect multiple phenotypes

Question 60

Epistasis

Answer 60

Interaction between two or more genes that control a single phenotype

Question 61

Genomic imprinting

Answer 61

When either the maternal or paternal allele is not expressed in the offspring

Question 62

Hemizygous

Answer 62

XY male who has one copy of a mutant allele on the X chromosome

Question 63

SNP

Answer 63

difference in one base pair at a particular site in the genome

Question 64

STR

Answer 64

site in the genome that consists of variable numbers of short repeated sequences

Question 65

Modifier genes

Answer 65

Genes which influence the expression of another. | THink epistasis