Units 11-18 Flashcards
(148 cards)
1
Q
Who was Gregor Mendel?
A
known as the father of modern genetics, began breeding peas to study patterns of inheritance
2
Q
Particulate Model of Inheritance
A
parents pass discrete particles (alleles) to offspring that do not blend
3
Q
Diploid
A
Two of each chromosome/gene
4
Q
Homologous chromosomes
A
pair of same chromosomes, one copy from each parent
5
Q
Haploid
A
1 of each chromosome, half the number you need
6
Q
Gamete
A
haploid eggs and sperm
7
Q
Gene
A
sequence of DNA that codes for a specific protein
8
Q
Alleles
A
different forms of the same gene
9
Q
Phenotype
A
outward physical appearance of an organism
10
Q
Genotype
A
a two letter combination of alleles (homologous)
11
Q
Allele pairings
A
two alleles in diploid cells
12
Q
Incomplete dominance
A
phenotype of heterozygote is intermediate between phenotype of two homozygous genotypes (red and white make pink flowers)
13
Q
Co-dominance
A
Phenotype of heterozygote simultaneously shows both phenotypes.
14
Q
Multiple alleles
A
two or more alleles for a gene
15
Q
Epistasis
A
1 gene affects the phenotype of another gene
ex: coat color in lab retrievers
16
Q
Pleiotropy
A
One gene with many effects on phenotype
ex: cystic fibrosis
17
Q
Polygenic Trait and how can you tell?
A
1 phenotype trait is controlled by many genes
The phenotypes form a normal distribution (bell shaped curve)
18
Q
Mendel’s Two Laws of Inheritance
A
Segregation of alleles: each egg or sperm gets only one allele. If two alleles, then 50/50
Independent Assortment: alleles at 1 gene assort independently of alleles at another gene
19
Q
Meiotic Drive
A
when an allele or chromosome is passed on more frequently than expected
20
Q
Autosomes
A
chromosomes not involved in sex determination
ex: sickle cell anemia
21
Q
Sex-linked traits
A
genes found on sex chromosomes show sex-specific patterns of inheritance
ex: hemophilia, red-green colorblindness, congenital night blindness, duchenne muscular dystrophy, fragile X syndrome
22
Q
Why are sex-linked traits important?
A
females can be carriers: heterozygote, phenotypes more common in males
23
Q
dosage compensation
A
Genetic mechanisms that equalize the expression of x-linked genes in males and females
24
Q
X chromosome inactivation
A
one female x chromosome shuts off, leaving one working copy
25
How do female cats get their mosaic fur colors?
fur color is x linked, different x alleles make different fur color
26
Heritability
amount of variation in a trait explained by genetics
27
environmental variance
amount of trait variation explained by environment and other random factors
28
phenotype plasticity
The ability of an organism with a given genotype to change its phenotype in response to an unpredictable environment
ex: many plants can either grow taller or wider depending on competition
in humans: muscles, skin color, height
29
biological evolution
non-random changes in genotype or allele frequencies across generations
30
5 micro-evolutionary forces
mutation, natural selection, sexual selection, gene flow, genetic drift
31
DNA mutations are the source of all
genetic variation
32
natural selection
differential survival and reproduction among individuals based on inherited characteristics
33
Fitness
ability to survive and reproduce
34
Adaptation
a trait that is or has been a target of natural or sexual selection
35
co-evolution
reciprocal adaptations in different species
36
Directional selection
favors one homozygote only
ex: galapagos, finches, during drought, selection favored larger beaked birds
37
Disruptive selection
selection favors both homozygotes
ex: african finches, selection favors birds with either large or small beaks, not medium
38
Stabilizing selection
selection favors heterozygotes or intermediates
ex: sickle cell heterozygotes favored because of resistance to malaria
39
Directional selection does what to genetic variation?
Eliminates it
40
Which two patterns of selection preserve genetic variation in a population?
disruptive and stabilizing
41
Disruptive selection could lead to what?
genetic divergence and possibly speciation
42
The flow of genetic information in Eukaryotes
DNA --- RNA --- Protein
43
DNA is transcribed into what?
mRNA: messenger RNA
44
Where does transcription occur?
nucleus
45
Does transcription occur on both strands of the DNA molecule?
Yes, but only one strand makes a protein
46
Sense transcript
mRNA transcript made into protein
47
Antisense transcript
NOT transcribed, could function in gene regulation
48
Ribozyme
RNA molecule that can do a chemical reaction, even its own splicing
49
What enzyme makes the messenger RNA molecule?
RNA polymerase
50
Amatoxins
toxic, blocks RNA polymerase. Found in amanita mushrooms...thermostable: cooking doesn't make it safe to eat
51
Ricin Poison
In castor beans, very toxic, breaks ribosomes so you cannot make proteins
52
Introns
RNA sequences removed from final mRNA by splicing, only in Eukaryotes
53
Exons
the expressed sequences, kept in the final mRNA
54
Splicing
Post-transcriptional editing in Eukaryotes, systematic removal of introns from the pre-mRNA to produce the final mRNA product
55
Alternative splicing could produce
slightly different proteins
56
Reverse transcriptase
Some RNA viruses can make DNA from RNA using this enzyme like HIV and Hepatitis B
57
Where does translation occur?
Cytoplasm
58
What is a codon?
a group of three mRNA bases
59
What does transfer RNA do?
carry amino acids to ribosomes
60
Actual site of translation
Ribosomes
61
What is an anticodon?
the tRNA complement to the mRNA codon
62
A protein is...
a chain or chains of amino acids
63
Post-translational Modification
changes to new protein that may be critical to its final function, like folding, phosphorylating....
64
Inteins
Protein segments removed from final protein
65
Exteins
Protein segments kept and spliced back together
66
Molecular Chaperones
often referred to as heat shock proteins
proteins that help other proteins fold or refold correctly
67
Synonymous mutation
a mutation does not change an animo acid (neutral)
68
Nonsynonymous Mutation
a mutation that changes an amino acid (not neutral)
69
What does gene expression mean?
the gene has gone through transcription and translation to make a protein
70
Does transcription require a primer?
no, RNA polymerase starts it
71
DNA Methylation
shuts genes off, methyl groups added to C and A nucleotides, are present in all cells and DNA except housekeeping genes, a major form of tissue specific gene regulation
72
What happens in positive regulation?
a transcriptional activator protein binds to DNA at 5 end to start transcription. without the activator, there is no transcription and the gene is off
73
What happens in negative regulation?
a repressor protein binds to DNA to block transcription. the gene is off until the repressor is removed. the SRY protein is a repressor protein.
74
Proteomics
the study of proteins
75
DNA microarray
can be used to measure gene expression for many/all genes simultaneously
76
Positive selection and example
best allele increases in frequency until it is fixed
LCT gene
77
Diversifying selection and example
selection that favors as much genetic variation as possible
Mhc genes
78
Balancing selection
two different alleles favored by selection
sickle cell
79
Sexual dimorphism
males and females are different --- they invest differently in reproduction
80
Anisogamy
eggs are large and costly; sperm are small and cheap
81
mating systems
evolve because degree of reproductive cooperation needed to raise offspring varies
82
monogamy
one male, one female
83
mate guarding
protect investment in reproduction, no extra pair copulation allowed
84
polyandry
one female, many males
85
sperm competition
in situations where several men might inseminate a single female, selection favors males w/ competitive sperm
*swimming speed important
86
Sperm should swim faster in ________ systems than in ___________ systems.
polyandrous, monogamous
87
Polygyny
one male, many females
88
How does polygyny affect testicles?
larger in polygynous males
89
aesthetic evolution
evolution that is driven by sensory judgement and cognitive choices
90
Display traits
behavior or phenotypes males use to attract females, might evolve because it stimulates females to invest more in reproduction
91
Mating preferences
how mate choice (female) drives the evolution of males display traits
92
Runaway sexual selection
female preference for exaggerated male traits could be maladaptive
93
Fitness indicator theory
sexual ornaments in males evolve so that females can judge the quality or fitness of potential male mates
94
Handicap Principle
males can signal greater fitness to females through handicapping traits, males who can afford the handicap have greater fitness
95
Intersexual conflict
arises when males try to remove female choice and control fertilization
96
Why concealed ovulation in humans?
could enhance female ability to influence male behavior
97
Modern Synthesis
Early 20th century reconciliation between Darwin's ideas, the work of Gregor Mendel, and the mathematical framework of population genetics to form modern evolutionary biology theory
98
Molecular evolution
evolution at the level of DNA sequences
99
Population genetics
the study of genetic changes within population variation and fixed genetic differences between populations, divergence
100
Genetic variation
genetic differences within a species
101
Genetic divergence
fixed genetic differences between species
102
Quantitative Genetics
the study of polygenic characteristics that show continuous phenotypic variation
103
Linkage Disequilibrium
The non-random association of alleles at different genes. Can be caused by physical linkage on chromosomes or natural selection for or against certain combinations of alleles on different chromosomes
104
What does it mean if an allele or mutation is 'fixed'?
it means that the allele is the only allele in the population and it has replaced all others
105
Fixed mutations are used ____
as genetic markers to identify human ancestors, dog breeds, and more
106
Selective Sweep
loss of genetic variation following positive selection
107
Purifying Selection
selection that favors one best allele, new alleles are worse and selected against
108
Balancing Selection
two different alleles are favored by selection
109
Diversifying Selection
Selection that favors as much genetic variation as possible
110
Neutral Allele
an allele that has no effect on the phenotype, because of this, their frequencies change randomly across generations
111
Neutral Molecular Evolution
allele frequencies are controlled by mutation and drift, not by selection
112
Molecular Clock Hypothesis
Neutral mutations fix at a constant rate in populations. That rate can be calibrated and used to estimate divergence time between different species.
113
Epigenetics
Variation in organisms that is not controlled by differences in DNA sequences. These changes are often controlled by changing how genes are transcribed without changing the DNA sequence.
114
adding methyl groups to a DNA sequence does what?
it changes how the DNA is transcribed and can shut it off.
115
Maternal Effects and why it occurs?
phenotype of offspring partly determined by genotype and environment of the mother
occurs because the mother has added something to the egg
116
There is no selection without ____
genetic variation
117
Populations ___, not _______
evolve, individuals
118
Selection acts on genotypes through ___
Phenotypes
119
Frequency-dependent natural selection
genotype fitness depends on frequency in the population
120
Positive fds
phenotypes are favored only when common.
ex: warning coloration
121
Negative fds
Phenotypes favored only when rare.
ex: left-handed fighting ability
122
Why doesn't Natural Selection completely eliminate harmful alleles/mutations?
a. recessive alleles can hide in heterozygotes
b. selection is different place to place
c. some alleles don't affect you until reproduction
d. fitness can be frequency dependent and can change
123
Law of the Battle
Intraspecific competition between males for access to females
124
Taste of the beautiful
female mate choice based on innate preferences for certain males
125
Red Queen hypothesis
with sexual reproduction, offspring are genetically different from their parents. sex allows organisms to be better adapted to the environment. co-evolution between host-parasite may select for sexual reproduction to reduce the risks of infection in hosts.
126
Gene flow
Movement of individuals from one population to another through mating
127
Gene flow prevents ______
speciation, populations cannot be genetically different
128
Without gene flow...
Populations become genetically different, probably most common way species form
129
Dispersal
Movement of individuals from their birth place to their own breeding area
130
Genetic drift
random changes in allele and genotype frequencies due to random events
*allele frequencies are more stable in larger populations
131
Population bottlenecks and founder effects
Severe reduction in population size, loss of genetic variation in new population
132
Effective Population Size
The average # of individuals in a population that contributes genes equally to the next generation
133
Artificial Selection
selection for specific traits by humans
134
How do we measure genetic variation in a population?
When you have more than one allele and all alleles are at a high frequency
135
Hardy Weinberg Equilibrium theory
the first null model for evolution, tells us how allele and genotype frequencies are removed with no evolution
136
How old are the primates?
55 mya
137
When is Human-Chimp divergence?
6 mya
138
Evolution leading to anatomically modern humans
Takes place around the African Rift Valley in East Africa
139
Persistence hunting is
the combination of running, walking, and tracking to chase prey until it collapses from exhaustion
140
Where is human genetic variation the greatest?
Africa
141
Where is the ancestral home for humans?
africa
142
Genetic ______ within populations is greater than genetic ____ between populations
variation, divergence
143
The SRGAP2 gene
leads to slower neocortex maturation gene duplications during Hominin Evolution increased size and complexity
144
What is the ancestral human skin color?
most likely light-colored skin
145
Two reasons why humans evolved dark skin?
a. in tropics, dark skin protects against sun damage
b. sunburn is a teratogen. it destroys folate levels, causing birth defects like Spina Bifida.
146
Why did humans evolve light skin?
allows skin to make Vitamin d during temperate zone winter
147
Which is an adaptation, dark or light skin?
both
148
Why is there phenotypic plasticity?
Because humans experience seasonality in sun exposure
