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Biology 180 > Bio 180: Evolution, Genetics > Flashcards

Bio 180: Evolution, Genetics Flashcards

For the first midterm of Biology 180

1
Q

Hypothesis

A

a proposed explanation of some phenomenon

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2
Q

Null Hypothesis

A

what one would expect to see if the hypothesis is incorrect or if the observations were due to chance

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3
Q

Prediction

A

a statement of what should be measured or observed if a hypothesis is correct

usually and “if…then” statement

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4
Q

Control Variable/Independent Variable

A

The variable being manipulated

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5
Q

Dependent Variable

A

the variable that is being measured

the variable where change should occur when the independent variable is manipulated

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6
Q

Theory

A

a proposed explanation for a very broad class of phenomenon or observations

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7
Q

Special Creation

A

leading explanation for the diversity of organisms in the mid 19th century

Pattern:

  1. species are independent/separate entities
  2. species do not change over time

Process:
each species was created separately and instantaneously at the same time by a divine being

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8
Q

Evolution

A

descent with modification

Pattern:

  1. species are created from a common ancestry; existing species descended from preexisting ones
  2. species change through time; characteristics of species can be modified from generation to generation

Process:
natural selection
Which was new, and the important part as to why Darwin and Wallace “discovered” evolution, they discovered the process

Explains:

  1. diversity of life and similarities of organisms
  2. adaptations to environments
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9
Q

Natural Selection

A

a genetically based change in the characteristics of a population over time

  1. traits vary among individuals in a population
  2. the individuals that are better suited/adapted to the environment will produce more surviving offspring (therefore passing on their genes) in the next generation than the individuals less adapted
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10
Q

Structural Homologies

A

similarities in the structures of different organisms

ie human arms and horse legs contain the same structure and same type of bones, but are obviously different
Turtles and humans are actually a really big one

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11
Q

Vestigial traits

A

reduced structures that have no or minimal function in one species but are clearly similar to functioning traits in another species

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12
Q

Developmental Homologies

A

similarities in morphology and cell fate in embryos

humans have tails in the embryo stage, as do most other animals, as well as gills

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13
Q

Genetic Homologies

A

similar protien and DNA sequences in different organisms

universality of basic genetic code

example: genes that control animal eyes and limbs, like in mice, flies, sharks squids and flatworks

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14
Q

Darwin’s Four Postulates

A
  1. Individuals within a population vary in traits
  2. At least some variation must be heritable and can be passed onto offspring
  3. Some individuals produce more offspring than others
  4. Individuals producing most offspring, not random subset of the population

The result is that the characteristics of a population will change over time

Condensed/Current View:
Natural selection occurs when heritable variation leads to differential reproduction

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15
Q

Darwinian Fitness/Fitness

A

the ability of an individual to produce offspring, relative to that ability in other individuals in the population

surviving offspring has greater importance than the offspring in general

the more surviving offspring, the “more fit” an individual is

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16
Q

Adaptation

A

a heritable trait that increases the fitness of an individual in a particular environment relative to individuals lacking the trait

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17
Q

Heredity

A

the transmission of traits from parents to offspring

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18
Q

Blending Inheritance

A

Carl Nageli

hereditary determinant from two parents blend in the offspring

black + white sheep = grey offspring sheep

does not support evolution because variation would quickly disappear if the traits blended

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19
Q

Inheritance of Acquired Characteristics

A

Jean Baptiste Lamarck

traits in parents that were modified through use are passed on to the next generation in modified form

emphasized adaptation to the environment
just through the wrong means (physical, not genetic)

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20
Q

Gregor Mendel

A

Worked out the rules of inheritance using the simplest possible way

used peas that for each trait only had two possible options (ie. seed shape was always either round or wrinkled)

Was the first person to really test past the F1 generation to see if recessive traits re-emerged

Also tested to see about traits being linked to one another, showed that they weren’t in the peas

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21
Q

Particulate Inheritance Hypothesis

A

Hereditary determinants (genes) maintain their integrity from generation to generation

  1. Do not blend together
  2. Do not acquire new or modified characteristics through use
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22
Q

Allele

A

alternative/different forms of a gene

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23
Q

The Principle of Dominance

A

In hybrids/heterozygous:
Dominant alleles are expressed
Recessive are present and can be passed on, but are not expressed

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24
Q

The Principle of Segregation

A

Two alleles of each gene must segregate (separate) into different gamete cells during the formation of egg and sperm in each parents

each gamete contains one allele of each gene

25
Homozygous
2 copies of the same allele
26
Heterozygous
2 different alleles for same gene
27
Genotype
alleles found in an individual
28
Phenotype
the observable traits/features of an individual
29
The Principle of Independent Assortment
Pairs of alleles (for different traits/genes) segregate independently from one another during gamete formation
30
Homologous Pair
Chromosomes that have similar size, shape and the same genes on them, but not necessarily the same alleles
31
Ploidy
Haplois, diploid, triploid the number of chromosome sets present 3 sets of 2 (the 2 is the ploidy) (2n)
32
Haploid Number
n number of distinct types of chromosomes found in a species 3 sets of 2 (3 is the haploid number) (2n, n is the haploid number)
33
Replicated vs. Unreplicated Chomorsomes
Replicated have two chromatids (sister chromosomes) that are held together at the/by the centromere unreplicated - 1 strand replicated - 2 strands
34
Chromatid and Sister Chromatids
A chromatid is what each copy of a replicated chromosome is called when two chromosomes are are exact matches and are held together, they are called sister chromatids
35
Meiosis
makes cell with 1/2 genetic material (can only have 1 of the 2 homologous pairs) for sexual reproduction/production of gametes in reproductive (germ) tissues --> when the egg and sperm cell combine, and embryo will get the other homologous pair and have the same total number of chromosomes as the parents
36
The Spindle
- built from microtubules - originate from centrosomes - radiate out from poles, meet in middle - move chromosomes
37
Crossing Over
- occurs in prophase I/synapsis - 2 non-sister chromatids physically exchange DNA - since alleles on 2 chromosomes may differ, leads to new genetic combinations on each chromosome
38
Separation and Distribution of Homologous Chromosomes
- occurs about in metaphase I - orientation of maternal vs. paternal chromosomes at equator is random - different gametes end up with different combinations of maternal and paternal chromosomes - 2^n different combinations possible
39
Fertilization
- in sexually reproducing species, gametes from different individuals combine to form offspring --> outcrossing - increases genetic diversity of offpsring
40
The Chromosomal Theory of Inheritance
1. Chromosomes carry Mendel's "hereditary determinants" or genes 2. Mendel's rules explained by independent segregation of homologous chromosomes at meiosis I is the Chromosomal Theory of Inheritance
41
Meiosis and the Principle of Segregation
Mendel's Principle of Segregation - two alleles of each gamate segregate (separate) into different gamete cells - each gamete contains one allele of each gene Explaination bases on process of Meiosis - one allele on maternal chromosome, other on paternal - Meiosis I: homologs (and alleles) -> different daughter cells -> different gametes - each gamete carries one allele for trait (not two)
42
Meiosis and the Principle of Independent Assortment
Mendel's Principle of Independent Assortment - pairs of alleles (for different traits/genes) segregate independently from one another during gamete formation Explanation based on the process of meiosis - when genes located on different chromosomes - meiosis I: each homologous pair lines-up independently of others - different genes assort independently of one another
43
Sex-Linked Inheritance
- discovered by Thomas Hunt Morgan through work with fruit flies - observed unusual patterns of inheritance - reciprocal crosses did not give same results
44
Inheritance of X-Linked Genes
genes that can be passed to both genders via the X chromosomes, usually passed from the mother X-Linked genes are more likely to appear in male offspring because they don't have a second X gene to offset problems
45
Linked Genes
genes that are on the same chromatid and are passed along together
46
Genetic Map
has relative positions of genetic loci in relation to each other/the length of the chromosome
47
Autosomes
Non-sex chromosomes
48
Incomplete Dominance
neither allele is dominant heterozygotes show a phenotype intermediate between the two homozygous phenotypes ``` RR = red Rr = pink rr = white ```
49
Codominance
both alleles are expressed at the same time heterozygotes have both the traits that homozygotes express, literally 1/2 and 1/2 Horse Hair: RR = red hair Rr = 1/2 red, 1/2 white rr = white hair
50
Multiple Alleles
existence of more then two alleles for/of the same gene one being still cannot carry more than two alleles of the same gene at a time, although hundred of alleles for that gene may exist
51
Pleitropy
when a single gene affects more than one phenotypic trait
52
Gene x Environment Interactions
When the environment effects the development of a gene's phenotype. Ex. Food deprivation on growth Ex. Temperature on certain rabbits fur and siamese cats fur
53
Epistasis
gene x gene interaction when phenotype produced by an allele depends on the actions of a gene at another loci Ex. Labrador retriever's colorings depends on how well the animal produces pigment and how well it get distributed in the hair
54
Polygenic Inheritance
When several loci contribute a small amount to a phenotype quantitative trait in humans, height, weight, skin color are all quantitative traits
55
Hardy-Weinberg Model Assumptions
1. No mutation - not existing alleles are converted into other existing alleles - no new alleles created 2. No migration - no new alleles added by immigration or removed by emigration 3. No "genetic drift" - no random/chance allele frequency changes 4. Random mating 5. No selection - all members of a parent population survive and contribute equal numbers of gametes to the gene pool
56
Hardy-Weinberg Model
Analyzes what happens to the frequencies of two alleles at the same genetic loci when evolutionary forces are NOT acting on a population Acts as a null hypothesis/control group
57
Hardy-Weinberg Principle
Allele frequencies do not change over time when transmitted according to the rules of Mendelian inheritance if allele frequencies are given by p and q, then genotype frequencies will be given by p^2, 2pq, and q^2 generation after generation as long as certain conditions apply
58
Hardy-Weinberg Equations
Use anytime: p + q = 1 p = frequency of AA + 1/2 frequency of Aa q = frequency of aa + 1/2 frequency of Aa When in HWE: f(AA) = p^2 f(Aa) = 2pq f(aa) = q^2 p^2 + 2pq + q^2 = 1

Biology 180 (5 decks)

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