Bio Chap 1

Question 1

What is euchromatin?

Answer 1

DNA that is transcriptionally active (relaxed)

Question 2

What is heterochromatin?

Answer 2

DNA that is transcriptionally inactive

Question 3

Describe Chromosomes

Answer 3

pairs of chromatids joined at centromere

Question 4

What are telomeres?

Answer 4

Telomeres at ends - high C-G content - buffer regions.

Question 5

What happens when Hayflick Limit is reached?

Answer 5

cell can no longer safely replicate - cell death

Question 6

What do karyotypes show?

Answer 6

Karyotypes detect chromosomal abnormalities ie. aneuploidy (absence or presence of extra chromosome) or structural abnormalities.. Deletion, duplication, inversion, substitution (region on one chromosome inserted into another), translocation (terminal regions of two diff chromosomes are swapped).

Question 7

What are the steps of karyotypes?

Answer 7

Cells are fixed at metaphase , viewed through microscope so they can be identified, photographed and realigned into a karyotype.

Question 8

What is a mispairing mutation?

Answer 8

• separation and failed re-attachment of two strands of DNA - mispairing of individual DNA nucleotides.

Question 9

What is polymorphism?

Answer 9

same locus/gene can give rise to many diff phenotypes (mutation).

Question 10

What is the law of segregation?

Answer 10

Alleles segregate equally into the 4 gametes during meiosis I and II.

Question 11

What is the law of independent assortment?

Answer 11

Genes from mom + dad assort independently into gametes during meiosis I.

Question 12

What is a monohybrid cross? Dihybrid?

Answer 12

One gene, dihybrid = two genes.

Question 13

What is a test cross?

Answer 13

reverse to determine genotype of organism (back cross) - use homozygous recessive genotype.

Question 14

What is X-linked inheritance?

Answer 14

dominant or recessive (must be on both x chromosomes or only one in male)

Question 15

What is codominance?

Answer 15

two diff alleles are expressed at same time.

Question 16

What is incomplete dominance?

Answer 16

blend of phenotypes

Question 17

What is penetrance?

Answer 17

frequency of individuals within a population with predicted phenotype (whether individual with genotype displays resulting phenotype).

Question 18

What is expressivity?

Answer 18

extent to which phenotypic trait is expressed in single individual (how strongly phenotype is expressed).

Question 19

What is complete penetrance?

Answer 19

Complete penetrance - all members with the genes for trait will express it. Reduced often occurs.

Question 20

What is variable expressivity?

Answer 20

Variable expressivity - how different members of pop with same traits express them at range of severities.

Question 21

What is genetic recombination? When does it not apply?

Answer 21

meiosis - homologous chromosomes swap alleles - especially true for far apart genes. Does not fully apply to linked genes - close together.

Question 22

What are map units? What are they related to?

Answer 22

Map units (centimorgans) - unit used to quantify distance between two genes on same chromosome. These are related to crossover frequency - frequency at which two genes are separately inherited. Gene mapping.

Question 23

What is extranuclear inheritance?

Answer 23

Mitochondria and chloroplast DNA.

Question 24

What is Natural Selection?

Answer 24

Survival of fittest → selective pressure on population. Differential reproduction results in increasing allele frequency of favorable alleles and adaptive traits in population.

Question 25

What is inbreeding?

Answer 25

members within population mate and reproduce with one another continuously - decreases variability of traits - decreases population success.

Question 26

What is outbreeding?

Answer 26

members of diff populations mate with one another - new variability - increase in reproductive fitness

Question 27

What is group selection? What is an example?

Answer 27

Group selection - groups that perform favorable behaviours promote reproductive success of group as whole. ie. Altruistic behaviours - group selection at play - reproductive success of individuals exhibiting behaviour may be diminished - behaviours increase fitness of species as whole

Question 28

What is genetic drift?

Answer 28

mechanism of allele frequency change most prominent when population faces no selective pressures. In absence of selection - random mutations give rise to new alleles can affect populations allele frequencies from generation to generation.

Question 29

What are inborn errors of metabolism?

Answer 29

Examples of deleterious mutations - inborn errors of metabolism - genetic disorders present at birth that disrupt production of key enzymes used in metabolic paths - ie. phenylketonuria - decreased ability to process phenylalanine.

Question 30

What is genetic leakage?

Answer 30

genetic leakage - occurs as genes are transferred between species - through inter-species breeding or incorporating intracellular genetic products like mitochondria DNA. Can lead to new mutations

Question 31

What is elimination and fixation?

Answer 31

Novel alleles may undergo elimination due to chance events, may undergo fixation.

Question 32

When are effects of genetic drift most pronounced? Give examples

Answer 32

Effects of genetic drift most pronounced when coupled with major changes in population makeup. ie. catastrophes will randomly remove variant alleles via bottleneck effect - small pool of survivors left to pass on lower diversity. Founder effect - small pops that branch off. Both result in decreased allelic diversity + more susceptible to further loss of alleles due to genetic drift - high amount of genetic diversity is favoured.

Question 33

What can evolutionary pressures result in?

Answer 33

Speciation

Question 34

What is the molecular clock?

Answer 34

method of dating evolutionary age of species based on frequency of allele changes - number of differences in genetic traits between two species is correlated with time since evolutionary divergence

Question 35

What is biometry?

Answer 35

statistical analysis of biological data.

Question 36

What are the conditions of HWE?

Answer 36

random mating, no natural selection, populations infinitely large, no gene flow (no migration), no genetic drift.