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biology - module 5 & 6 > chapter 20 - patterns of inheritance > Flashcards

chapter 20 - patterns of inheritance Flashcards

1
Q

What is a diploid?

A
  • an organism with a pair of homologous chromosomes, it has 2 alleles of each gene
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2
Q

What is a gene?

A
  • a sequence of dna that codes for a protein
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3
Q

What is a allele?

A
  • A variation of a gene
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4
Q

What is a genotype?

A
  • the combination of alleles that an organism has
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5
Q

What is a phenotype?

A
  • the physical expression of the genotype and its interaction with the enviornment (skin colour)
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6
Q

What is a dominant allele?

A
  • Its an allele that is always expressed in the phenotype
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7
Q

What is a recessive allele?

A
  • alleles that are only expressed when homozygous
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8
Q

What are codominant alleles?

A
  • both alleles are expressed in the phenotype, phenotype is intermediate for both alleles
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9
Q

What is meant by homozygous?

A
  • When both alleles are the same
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10
Q

What is meant by heterozygous?

A
  • when both alleles are not the same
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11
Q

What is the locus?

A
  • the location of a gene on a chromosome
  • alleles of the same genes always have the same locus
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12
Q

What is monohybrid inheritance?

A
  • inheritance of a characteristic controlled by a single gene
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13
Q

What is dihybrid inheritance?

A
  • inheritance of two characteristics controlled by two separate genes
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14
Q

What are the phenotypic ratios for both monohybrid and dihybrid inheritance?

A
  • monohybrid - 3:1
  • dihybrid - 9:3:3:1
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15
Q

How do the gametes differ in codominance compared to both monohybrid and dihybrid inheritance?

A
  • the gametes are heterozygous whereas in monohybrid and dihybrid the gametes are homozygous
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16
Q

What is an autosome?

A
  • all the non sex chromosomes
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17
Q

what is autosomal linkage?

A
  • its where genes that are on the same autosome are linked
  • they will stay together during independant assortment and will be inherited together
  • affects the typical phenotypic ratio(9:3:3:1)
  • because linked genes are inherited together they behave more like monohybrid cross (3:1)
  • autosomal linkage means that more offspring will have the same genotype and phenotype as their parents
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18
Q

What may cause the offspring to not have the same genotype and phenotype?

A
  • the alleles are separated during crossing over
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19
Q

What makes genes more closely related?

A
  • the closer their loci of genes on an autosome, the more closely linked they are
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20
Q

What is a homologous pair?

A
  • same genes
  • different alleles
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21
Q

What is sex linkage?

A
  • the expression of alleles located on sex chromosomes depends on the sex of the individual
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22
Q

What type of chromosomes do females and males have and what is the difference between them?

A
  • females have XX chromosomes
  • males have XY chromosomes
  • the Y chromosome is smaller than X and is missing more genes present on X
23
Q

What is required in the chromosomes of males and females for them to have haemophilia?

A
  • females, must be homozygous recessive to be a sufferer
  • males, the one X chromosome they have must be the faulty allele to be a sufferer
24
Q

What is epistasis and when does it happen?

A
  • its an interaction between genes . . . when the expression of one gene surpresses the expression of another gene
  • it happens when a phenotype is controlled by more than one gene
25
Q

What affect does epistasis have on dihybrid crosses?

A
  • it changes the typical phenotypic ratio (9:3:3:1)
  • if recessive epistatic alleles(9:3:4)
  • if dominant epistatic alleles(12:3:1)
26
Q

What changes the normal phenotypic ratios

A
  • autosomal linkage
  • sex linkage
  • epistasis
27
Q

What is genetic bottleneck effect?
Is it in the same geographical location or not?

A
  • we start with a ancestral population
  • theres a big decrease in the population this could be due to hunting
  • happens in the same geographical location
28
Q

What does the genetic bottleneck effect result in?

A
  • few individuals survive
  • decrease in genetic diversity, meaning fewer alleles in surviving population
  • inbreeding
  • genetic drift has a greater effect on smaller populations
29
Q

What is founder effect?
Is it in the same geographical location or not?

A
  • where a few organisms in a population become separated and create a new colony
  • this can happen because the organisms get lost or environmental factors prevent them from staying within their population
  • it happens in different geographical locations
30
Q

What does the founder effect result in ?

A
  • new colony formed by a small number of individuals
  • genetic diversity decreased
  • inbreeding
  • genetic drift has a greater effect on smaller populations
  • founders have few alleles
31
Q

What is genetic drift?

A
  • changes in allele frequency between generations due to random chance (e.g random fertilisation)
32
Q

What is meant by random fertilisation?

A
  • the allele passed to the zygote is random
33
Q

What is a species?

A
  • organisms that can reproduce to produce fertile offspring
33
Q

What is a gene pool?

A
  • all the alleles present in a population
34
Q

What is the difference between a population and a community?

A
  • population, all the organisms of a single species in one place at a time
  • community, all the organisms of all the species in one place at one time
35
Q

What is allele frequency?

A
  • how common an allele is in the population
36
Q

what is evolution with regards to this topic?

A
  • a change in allele frequency overtime
37
Q

What is meant by differential reproductive success?

A
  • organisms with a phenotype better adapted to their enviornment have selective advantage and are more likely to survive and reproduce
38
Q

what is speciation?

A
  • the process of forming a new species
39
Q

What is the hardy weinberg principle?

A
  • a model that predicts the frequency of alleles, genotypes and phenotypes in a population
40
Q

What does the hard weinberg principle predict?

A
  • the frequency of alleles of a gene will stay constant over generations
41
Q

What are assumptions does the hardy weinberg principle assume?

A
  • no mutations
  • no selection
  • random mating
  • large population(no genetic drift )
  • no migration
42
Q

When does speciation occur?

A
  • it happens when populations become reproductively isolated(no gene flow between them)
43
Q

What are the two types of speciation and what is the difference?

A
  • allopatric speciation, geographical isolation leading to reproductive isolation
  • sympatric isolation, non geographical isolation leading to reproductive isolation
44
Q

What are some examples of sympatric speciation and allopatric speciation?

A
  • allopatric speciation, a river could separate two populations and so that isolates reproduction
  • sympatric speciation, examples include:
  • seasonal, reproductively active at different times of the year
  • behavioural, different courtship behaviour
  • hybrid sterility, hybrids of two parents are infertile
  • morphological, different shaped genatlia
45
Q

What does speciation result in?

A
  • variation exists in the population(s) due to mutations
  • causes a change in allele frequency
  • occurs over many generations(dodo)
  • directional reproductive success
  • different selection pressures and so directional selection of different phenotypes
46
Q

What is artificial selection?

A
  • when humans interbreed organisms with useful traits(phenotype) to improve their usefulness
47
Q

What are some examples of artificial selection?

A
  • dairy cows
  • corn
  • pedigree dogs
48
Q

Explain how artificial selection is used in cows?

A
  • a female with a desired trait is selected(high milk yield, high quality, disease resistant)
  • select a male with a mother with desired trait
  • cross breed them
  • select the offspring with the highest trait
    -repeat the process over many generations
49
Q

Explain how artificial selection is used in corn?

A
  • select plants with desirable trait (large ears of grain)
  • cross breed them
  • select offspring with the best desirable trait
  • repeat over many generations
50
Q

What are the advantages of artificial selection?

A
  • increase in frequency of desirable traits
  • bigger/amplified traits
  • more efficient farming
51
Q

What are the disadvantages of artificial selection?

A
  • reduced genetic diversity
  • increased expression of genetic disorders, as inbreeding results in the expression of recessive alleles
  • ethical issues, pugs can breathe properly
52
Q
A

biology - module 5 & 6 (12 decks)

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