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Biology 1102 > Units 11-18 > Flashcards

Units 11-18 Flashcards

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1
Q

Who was Gregor Mendel?

A

known as the father of modern genetics, began breeding peas to study patterns of inheritance

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2
Q

Particulate Model of Inheritance

A

parents pass discrete particles (alleles) to offspring that do not blend

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3
Q

Diploid

A

Two of each chromosome/gene

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4
Q

Homologous chromosomes

A

pair of same chromosomes, one copy from each parent

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5
Q

Haploid

A

1 of each chromosome, half the number you need

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6
Q

Gamete

A

haploid eggs and sperm

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7
Q

Gene

A

sequence of DNA that codes for a specific protein

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8
Q

Alleles

A

different forms of the same gene

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9
Q

Phenotype

A

outward physical appearance of an organism

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10
Q

Genotype

A

a two letter combination of alleles (homologous)

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11
Q

Allele pairings

A

two alleles in diploid cells

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12
Q

Incomplete dominance

A

phenotype of heterozygote is intermediate between phenotype of two homozygous genotypes (red and white make pink flowers)

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13
Q

Co-dominance

A

Phenotype of heterozygote simultaneously shows both phenotypes.

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14
Q

Multiple alleles

A

two or more alleles for a gene

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15
Q

Epistasis

A

1 gene affects the phenotype of another gene
ex: coat color in lab retrievers

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16
Q

Pleiotropy

A

One gene with many effects on phenotype
ex: cystic fibrosis

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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)

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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

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19
Q

Meiotic Drive

A

when an allele or chromosome is passed on more frequently than expected

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20
Q

Autosomes

A

chromosomes not involved in sex determination
ex: sickle cell anemia

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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

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22
Q

Why are sex-linked traits important?

A

females can be carriers: heterozygote, phenotypes more common in males

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23
Q

dosage compensation

A

Genetic mechanisms that equalize the expression of x-linked genes in males and females

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24
Q

X chromosome inactivation

A

one female x chromosome shuts off, leaving one working copy

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25
Q

How do female cats get their mosaic fur colors?

A

fur color is x linked, different x alleles make different fur color

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26
Q

Heritability

A

amount of variation in a trait explained by genetics

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27
Q

environmental variance

A

amount of trait variation explained by environment and other random factors

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28
Q

phenotype plasticity

A

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

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29
Q

biological evolution

A

non-random changes in genotype or allele frequencies across generations

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30
Q

5 micro-evolutionary forces

A

mutation, natural selection, sexual selection, gene flow, genetic drift

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31
Q

DNA mutations are the source of all

A

genetic variation

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32
Q

natural selection

A

differential survival and reproduction among individuals based on inherited characteristics

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33
Q

Fitness

A

ability to survive and reproduce

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34
Q

Adaptation

A

a trait that is or has been a target of natural or sexual selection

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35
Q

co-evolution

A

reciprocal adaptations in different species

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36
Q

Directional selection

A

favors one homozygote only
ex: galapagos, finches, during drought, selection favored larger beaked birds

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37
Q

Disruptive selection

A

selection favors both homozygotes
ex: african finches, selection favors birds with either large or small beaks, not medium

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38
Q

Stabilizing selection

A

selection favors heterozygotes or intermediates
ex: sickle cell heterozygotes favored because of resistance to malaria

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39
Q

Directional selection does what to genetic variation?

A

Eliminates it

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40
Q

Which two patterns of selection preserve genetic variation in a population?

A

disruptive and stabilizing

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41
Q

Disruptive selection could lead to what?

A

genetic divergence and possibly speciation

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42
Q

The flow of genetic information in Eukaryotes

A

DNA — RNA — Protein

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43
Q

DNA is transcribed into what?

A

mRNA: messenger RNA

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44
Q

Where does transcription occur?

A

nucleus

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45
Q

Does transcription occur on both strands of the DNA molecule?

A

Yes, but only one strand makes a protein

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46
Q

Sense transcript

A

mRNA transcript made into protein

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47
Q

Antisense transcript

A

NOT transcribed, could function in gene regulation

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48
Q

Ribozyme

A

RNA molecule that can do a chemical reaction, even its own splicing

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49
Q

What enzyme makes the messenger RNA molecule?

A

RNA polymerase

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50
Q

Amatoxins

A

toxic, blocks RNA polymerase. Found in amanita mushrooms…thermostable: cooking doesn’t make it safe to eat

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51
Q

Ricin Poison

A

In castor beans, very toxic, breaks ribosomes so you cannot make proteins

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52
Q

Introns

A

RNA sequences removed from final mRNA by splicing, only in Eukaryotes

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53
Q

Exons

A

the expressed sequences, kept in the final mRNA

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54
Q

Splicing

A

Post-transcriptional editing in Eukaryotes, systematic removal of introns from the pre-mRNA to produce the final mRNA product

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55
Q

Alternative splicing could produce

A

slightly different proteins

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56
Q

Reverse transcriptase

A

Some RNA viruses can make DNA from RNA using this enzyme like HIV and Hepatitis B

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57
Q

Where does translation occur?

A

Cytoplasm

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58
Q

What is a codon?

A

a group of three mRNA bases

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59
Q

What does transfer RNA do?

A

carry amino acids to ribosomes

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60
Q

Actual site of translation

A

Ribosomes

61
Q

What is an anticodon?

A

the tRNA complement to the mRNA codon

62
Q

A protein is…

A

a chain or chains of amino acids

63
Q

Post-translational Modification

A

changes to new protein that may be critical to its final function, like folding, phosphorylating….

64
Q

Inteins

A

Protein segments removed from final protein

65
Q

Exteins

A

Protein segments kept and spliced back together

66
Q

Molecular Chaperones

A

often referred to as heat shock proteins
proteins that help other proteins fold or refold correctly

67
Q

Synonymous mutation

A

a mutation does not change an animo acid (neutral)

68
Q

Nonsynonymous Mutation

A

a mutation that changes an amino acid (not neutral)

69
Q

What does gene expression mean?

A

the gene has gone through transcription and translation to make a protein

70
Q

Does transcription require a primer?

A

no, RNA polymerase starts it

71
Q

DNA Methylation

A

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
Q

What happens in positive regulation?

A

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
Q

What happens in negative regulation?

A

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
Q

Proteomics

A

the study of proteins

75
Q

DNA microarray

A

can be used to measure gene expression for many/all genes simultaneously

76
Q

Positive selection and example

A

best allele increases in frequency until it is fixed
LCT gene

77
Q

Diversifying selection and example

A

selection that favors as much genetic variation as possible
Mhc genes

78
Q

Balancing selection

A

two different alleles favored by selection
sickle cell

79
Q

Sexual dimorphism

A

males and females are different — they invest differently in reproduction

80
Q

Anisogamy

A

eggs are large and costly; sperm are small and cheap

81
Q

mating systems

A

evolve because degree of reproductive cooperation needed to raise offspring varies

82
Q

monogamy

A

one male, one female

83
Q

mate guarding

A

protect investment in reproduction, no extra pair copulation allowed

84
Q

polyandry

A

one female, many males

85
Q

sperm competition

A

in situations where several men might inseminate a single female, selection favors males w/ competitive sperm
*swimming speed important

86
Q

Sperm should swim faster in ________ systems than in ___________ systems.

A

polyandrous, monogamous

87
Q

Polygyny

A

one male, many females

88
Q

How does polygyny affect testicles?

A

larger in polygynous males

89
Q

aesthetic evolution

A

evolution that is driven by sensory judgement and cognitive choices

90
Q

Display traits

A

behavior or phenotypes males use to attract females, might evolve because it stimulates females to invest more in reproduction

91
Q

Mating preferences

A

how mate choice (female) drives the evolution of males display traits

92
Q

Runaway sexual selection

A

female preference for exaggerated male traits could be maladaptive

93
Q

Fitness indicator theory

A

sexual ornaments in males evolve so that females can judge the quality or fitness of potential male mates

94
Q

Handicap Principle

A

males can signal greater fitness to females through handicapping traits, males who can afford the handicap have greater fitness

95
Q

Intersexual conflict

A

arises when males try to remove female choice and control fertilization

96
Q

Why concealed ovulation in humans?

A

could enhance female ability to influence male behavior

97
Q

Modern Synthesis

A

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
Q

Molecular evolution

A

evolution at the level of DNA sequences

99
Q

Population genetics

A

the study of genetic changes within population variation and fixed genetic differences between populations, divergence

100
Q

Genetic variation

A

genetic differences within a species

101
Q

Genetic divergence

A

fixed genetic differences between species

102
Q

Quantitative Genetics

A

the study of polygenic characteristics that show continuous phenotypic variation

103
Q

Linkage Disequilibrium

A

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
Q

What does it mean if an allele or mutation is ‘fixed’?

A

it means that the allele is the only allele in the population and it has replaced all others

105
Q

Fixed mutations are used ____

A

as genetic markers to identify human ancestors, dog breeds, and more

106
Q

Selective Sweep

A

loss of genetic variation following positive selection

107
Q

Purifying Selection

A

selection that favors one best allele, new alleles are worse and selected against

108
Q

Balancing Selection

A

two different alleles are favored by selection

109
Q

Diversifying Selection

A

Selection that favors as much genetic variation as possible

110
Q

Neutral Allele

A

an allele that has no effect on the phenotype, because of this, their frequencies change randomly across generations

111
Q

Neutral Molecular Evolution

A

allele frequencies are controlled by mutation and drift, not by selection

112
Q

Molecular Clock Hypothesis

A

Neutral mutations fix at a constant rate in populations. That rate can be calibrated and used to estimate divergence time between different species.

113
Q

Epigenetics

A

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
Q

adding methyl groups to a DNA sequence does what?

A

it changes how the DNA is transcribed and can shut it off.

115
Q

Maternal Effects and why it occurs?

A

phenotype of offspring partly determined by genotype and environment of the mother
occurs because the mother has added something to the egg

116
Q

There is no selection without ____

A

genetic variation

117
Q

Populations ___, not _______

A

evolve, individuals

118
Q

Selection acts on genotypes through ___

A

Phenotypes

119
Q

Frequency-dependent natural selection

A

genotype fitness depends on frequency in the population

120
Q

Positive fds

A

phenotypes are favored only when common.
ex: warning coloration

121
Q

Negative fds

A

Phenotypes favored only when rare.
ex: left-handed fighting ability

122
Q

Why doesn’t Natural Selection completely eliminate harmful alleles/mutations?

A

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
Q

Law of the Battle

A

Intraspecific competition between males for access to females

124
Q

Taste of the beautiful

A

female mate choice based on innate preferences for certain males

125
Q

Red Queen hypothesis

A

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
Q

Gene flow

A

Movement of individuals from one population to another through mating

127
Q

Gene flow prevents ______

A

speciation, populations cannot be genetically different

128
Q

Without gene flow…

A

Populations become genetically different, probably most common way species form

129
Q

Dispersal

A

Movement of individuals from their birth place to their own breeding area

130
Q

Genetic drift

A

random changes in allele and genotype frequencies due to random events
*allele frequencies are more stable in larger populations

131
Q

Population bottlenecks and founder effects

A

Severe reduction in population size, loss of genetic variation in new population

132
Q

Effective Population Size

A

The average # of individuals in a population that contributes genes equally to the next generation

133
Q

Artificial Selection

A

selection for specific traits by humans

134
Q

How do we measure genetic variation in a population?

A

When you have more than one allele and all alleles are at a high frequency

135
Q

Hardy Weinberg Equilibrium theory

A

the first null model for evolution, tells us how allele and genotype frequencies are removed with no evolution

136
Q

How old are the primates?

A

55 mya

137
Q

When is Human-Chimp divergence?

A

6 mya

138
Q

Evolution leading to anatomically modern humans

A

Takes place around the African Rift Valley in East Africa

139
Q

Persistence hunting is

A

the combination of running, walking, and tracking to chase prey until it collapses from exhaustion

140
Q

Where is human genetic variation the greatest?

A

Africa

141
Q

Where is the ancestral home for humans?

A

africa

142
Q

Genetic ______ within populations is greater than genetic ____ between populations

A

variation, divergence

143
Q

The SRGAP2 gene

A

leads to slower neocortex maturation gene duplications during Hominin Evolution increased size and complexity

144
Q

What is the ancestral human skin color?

A

most likely light-colored skin

145
Q

Two reasons why humans evolved dark skin?

A

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
Q

Why did humans evolve light skin?

A

allows skin to make Vitamin d during temperate zone winter

147
Q

Which is an adaptation, dark or light skin?

A

both

148
Q

Why is there phenotypic plasticity?

A

Because humans experience seasonality in sun exposure

Biology 1102 (3 decks)

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