Genetics & Evolution Flashcards
(72 cards)
1
Q
genetics
A
study of how traits are inherited from one generation to the next
2
Q
genes
A
composed of DNA and are located on chromosomes
3
Q
Mendel’s First Law (law of segregation)
A
- genes exist in alternative forms, a gene controls a specific trait
- organism has 2 alleles for each trait
- the 2 alleles segregate during meiosis, resulting in gametes that carry 1 allele
- if 2 alleles are different, 1 will be dominant, and the other will be recessive
4
Q
Mendel’s Law of Dominance
A
dominant allele is expressed in the phenotype
5
Q
Mendel’s Second Law (law of independent assortment)
A
- inheritance of one trait is completely independent of any other
- modern genetics: genes on the same chromosome will not follow this rule and will stay together unless crossing over occurs
6
Q
incomplete dominance
A
- progeny phenotypes are blends of parental phenotypes
- heterozygote is an intermediate of the phenotypes of the homozygotes
7
Q
codominance
A
- multiple alleles exist for a given gene and more than one of them is dominant
- ex: ABO blood groups, Ia and Ib are codominant and produce IaIb blood type
8
Q
sex determination
A
- women have XX, men have XY
- gender of a zygote is determined by the contribution of the male gamete (if sperm carries and X or a Y)
- sex-linked: genes located on the X or Y chromosomes
9
Q
sex linkage
A
- recessive genes carried on the X chromosome will produce the recessive phenotypes when they occur in men, ex: hemophilia and color blindness
- sex linked recessives generally affect only men, can be passed from grandfather to grandson via a daughter who is a carrier
10
Q
nondisjunction
A
-failure of homologous chromosomes to separate properly during meiosis I or failure of sister chromatids to separate properly during meiosis II
11
Q
trisomy
A
3 copies of a chromosome, ex: Down syndrome
12
Q
monosomy
A
1 copy of a chromosome
13
Q
chromosomal breakage
A
may occur spontaneously or by environmental factors such as mutagenic agents and X-rays
14
Q
mutagenic agents
A
- induce mutations
- cosmic rays, X-rays, UV rays, and radioactivity, colchicine, or mustard gas
- sometimes also carcinogenic (cancer-causing)
15
Q
point mutation
A
nucleic acid is replaced by another nuclei acid, affects between 1-3 nucleotides
16
Q
silent mutation
A
the new codon codes for the same AA and no change is seen
17
Q
missense mutation
A
new codon codes for a new AA, may or may not lead to problems in the resulting protein
18
Q
nonsense mutation
A
new codon is a stop codon, lethal or severely inhibit the function
19
Q
frameshift mutation
A
nucleic acids are deleted or inserted, often lethal bc it throw off entire sequence
20
Q
examples of genetic disorders
A
- phenylketonuria (PKU): inability to produce the enzyme for the metabolism of phenylalanine
- sickle cell anemia: RBCs become crescent shaped, substitution of valine for glutamic acid
21
Q
bacterial genome
A
- consists of a singular circular chromosome located in the nucleic region of the cell
- also contain smaller rings of DNA called plasmids
22
Q
episomes
A
plasmids that are capable of integration into the bacterial genome
23
Q
replication of bacterial chromosomes
A
- begins at a unique origin of replication and proceeds in both directions
- DNA is synthesized in the 5’-3’ direction
24
Q
binary fission
A
- process by which bacterial cells reproduce
- asexual process
25
transformation
-a foreign chromosome fragment (plasmid) is incorporated into the bacterial chromosome via recombination, creating new inheritable genetic combinations
26
conjugation
- transfer of genetic material b/w 2 bacteria (that have a sex factor) that are temporarily joined
- genetic material is transferred from the donor male (+) to the recipient female (-)
27
F factor
- best studied sex factor
- F+ contain this plasmid, F- does not
- F+ replicates its F factor and donates the copy to F-
28
antibody resistance
genes that code for other characteristics may be found on the plasmids
29
Hfr cells (high frequency of recombination)
- bacterial chromosome replicates during conjugations and starts to move from donor to recipient
- bridge usually breaks before the entire chromosome is transferred but the bacterial genes that enter the recipient cell can easily recombine with the genes already present
30
transduction
- bacteriophage infects its host bacterium by injecting its viral DNA into the bacterium
- fragments of bacterial chromosome become packaged into the viral progeny
31
regulation of transcription
- based on the accessibility of RNA Pol to the genes being transcribed
- directed by an operon, which consists of structural genes, operator region, and a promoter region
32
operator
sequence of non transcribable DNA that is the repressor binding site
33
promoter
noncoding sequence of of DNA that serves as the initial binding site for RNA Pol
34
regulator gene
codes for the synthesis of a repressor molecule that binds to the operator and blocks RNA Pol from transcribing genes
35
inducible systems
- repressor binds to the operator, forming a barrier that prevents RNA Pol from transcribing structural genes
- for txn to occur, an inducer must bind to the repressor to prevent binding to the operator
36
repressible systems
- repressor is inactive until it binds with the corepressor
| - prevents txn only if a repressor-corepressor complex is formed
37
constitutive
operons containing mutations that make it incapable of turning off, are always synthesized
38
Lamarckian evolution
- new organs or changes in existing ones arose because of needs of the organism (disproved theory)
- based on use or disuse
- acquired characteristic, ex: giraffes with long necks bc of excessive use of them
39
Darwin's Theory of Natural Selection
- pressures in the environment select for the organism most fit to survive and reproduce
- genes of parents more fit are passed to more offspring and become more prevalent
40
overpopluation
more offspring produce than can survive
41
variations
offspring naturally show differences in their characteristics
42
competition
population must compete for the necessities of life
43
speciation
- evolution of new species
- genetic variation, changes in environment, migration to new environments, adaptation, natural selection, genetic drift, and isolation lead to speciation
44
demes
- small, local populations that form within a species
| - if deme becomes isolated, speciation may occur
45
covergent evolution
-when 2 species from different ancestors develop similar traits
46
parallel evolution
-similar to convergent evolution, but a more recent ancestor can be identified
47
divergent evolution
-species with shared ancestors develop differing traits die to different environments
48
adaptive radiation
- emergence of a number of lineages from a single ancestral species
- differences b/w them are those adaptive to a distinct lifestyle or niche
49
population
all members of a particular species inhabiting a given location
50
gene pool
sum total of all the alleles for any given trait in the population
51
gene frequency
decimal fraction representing the presence of an allele for all members of a population that have this particular gene
52
p
frequency of the dominant allele
53
q
frequency of the recessive allele
54
p+q=
1
55
Hardy-Weinberg principle
```
ideal conditions:
pop is large
no mutations
mating is random
no migration
genes are all equally successful at reproducing
```
56
p^2+2pq+q^2=1
```
p^2= dominant homozygous (TT)
pq= heterozygote (Tt)
q^2= recessive homozygous (tt)
```
57
microevolution
- no population stays in the Hardy-Weinberg equilibrium
| - agents of microevolutionary change: natural selection, mutation, assortive mating, genetic drift, gene flow
58
assortive mating
if mates are not randomly chosen but rather selected according to criteria such a phenotype and proximity (sexual selection), the relative genotype ratios will be affected and will depart from the predictions of the Hardy-Weinberg equilibrium
59
genetic drift
- changes in the composition of the gene pool due to chance
| - more profound in small or new populations, founder effect
60
gene flow
migration of individuals will result in a loss or gain of genes, changing the gene pool
61
types of fossils
- actual remains: teeth, bones, amber (fossil resin of trees)
- petrification: mineral replace the cells
- imprints: impressions (footprints)
- molds: hollow spaces in rocks
- casts: mineral deposits in mold
62
homologous structures
same basic anatomical features, similar evolutionary patterns, ex: arms of a human, wings of a bat
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analogous structures
similar functions but different evolutionary origins and patterns of development, ex: wings of a fly and wings of a bird
64
comparative embryology
- stages of development of the embryo resemble the stages of evolutionary history
- earlier the stage at which the development begins to diverge, the more dissimilar the adult organisms will be
65
comparative biochemistry
-most organisms demonstrate the same basic needs and metabolic processes
-similarity of enzymes involved in these processes mean
all organisms contain some DNA sequences in common
66
vestigial structures
- have no known function but had some ancestral function
| - ex: appendix
67
geographic barriers
-barriers increase the likelihood of genetic adaptations on either side, each population may evolve specific adaptations for their environment
68
primordial soup
-theory suggest that life began in a pond or ocean as a result of the combination of chemicals from the atmosphere and some form of energy to make amino acids, the building blocks of proteins, which would then evolve into all the species
69
coacervate droplets
- cluster of colloidal protein molecules
| - small percentage of the droplets with favorable characteristics may have developed into the first primitive cells
70
development of autotrophs
heterotrophs slowly evolved complex biochemical pathways and anaerobic respiratory processes to convert nutrients into energy
71
development of aerobic respiration
once molecular oxygen became part of the earths atmosphere, heterotrophs and autotrophs evolved biochemical pathways of aerobic respiration
72
4 categories of living organisms
1. autotrophic anaerobes: chemosynthetic bacteria
2. autotrophic aerobes: green plants
3. heterotrophic anaerobes : yeasts
4. heterotrophic aerobes: humans, earthworms, amoeba
