Bio Chap 1 Flashcards
What is euchromatin?
DNA that is transcriptionally active (relaxed)
What is heterochromatin?
DNA that is transcriptionally inactive
Describe Chromosomes
pairs of chromatids joined at centromere
What are telomeres?
Telomeres at ends - high C-G content - buffer regions.
What happens when Hayflick Limit is reached?
cell can no longer safely replicate - cell death
What do karyotypes show?
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).
What are the steps of karyotypes?
Cells are fixed at metaphase , viewed through microscope so they can be identified, photographed and realigned into a karyotype.
What is a mispairing mutation?
- separation and failed re-attachment of two strands of DNA - mispairing of individual DNA nucleotides.
What is polymorphism?
same locus/gene can give rise to many diff phenotypes (mutation).
What is the law of segregation?
Alleles segregate equally into the 4 gametes during meiosis I and II.
What is the law of independent assortment?
Genes from mom + dad assort independently into gametes during meiosis I.
What is a monohybrid cross? Dihybrid?
One gene, dihybrid = two genes.
What is a test cross?
reverse to determine genotype of organism (back cross) - use homozygous recessive genotype.
What is X-linked inheritance?
dominant or recessive (must be on both x chromosomes or only one in male)
What is codominance?
two diff alleles are expressed at same time.
What is incomplete dominance?
blend of phenotypes
What is penetrance?
frequency of individuals within a population with predicted phenotype (whether individual with genotype displays resulting phenotype).
What is expressivity?
extent to which phenotypic trait is expressed in single individual (how strongly phenotype is expressed).
What is complete penetrance?
Complete penetrance - all members with the genes for trait will express it. Reduced often occurs.
What is variable expressivity?
Variable expressivity - how different members of pop with same traits express them at range of severities.
What is genetic recombination? When does it not apply?
meiosis - homologous chromosomes swap alleles - especially true for far apart genes. Does not fully apply to linked genes - close together.
What are map units? What are they related to?
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.
What is extranuclear inheritance?
Mitochondria and chloroplast DNA.
What is Natural Selection?
Survival of fittest → selective pressure on population. Differential reproduction results in increasing allele frequency of favorable alleles and adaptive traits in population.
What is inbreeding?
members within population mate and reproduce with one another continuously - decreases variability of traits - decreases population success.
What is outbreeding?
members of diff populations mate with one another - new variability - increase in reproductive fitness
What is group selection? What is an example?
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
What is genetic drift?
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.
What are inborn errors of metabolism?
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.
What is genetic leakage?
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
What is elimination and fixation?
Novel alleles may undergo elimination due to chance events, may undergo fixation.
When are effects of genetic drift most pronounced? Give examples
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.
What can evolutionary pressures result in?
Speciation
What is the molecular clock?
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
What is biometry?
statistical analysis of biological data.
What are the conditions of HWE?
random mating, no natural selection, populations infinitely large, no gene flow (no migration), no genetic drift.
