Genetics Flashcards
(161 cards)
1
Q
Genetics definition
A
“Study of heredity and variation”
2
Q
Genetics principles account for
A
“Diversity of organisms
3
Q
What provides opportunities for species to adapt and evolve?
A
“Sexual reproduction”
4
Q
Who laid down the basic laws of genetics?
A
“Gregor Mendel”
5
Q
When were the basic laws of genetics laid down?
A
“1866”
6
Q
Who named Mendel’s factors ‘genes’?
A
“Johannsen”
7
Q
When were Mendel’s factors named ‘genes’?
A
“1909”
8
Q
Who showed genes are carried on chromosomes?
A
“Thomas Morgan”
9
Q
When was it shown that genes are carried on chromosomes?
A
“1912”
10
Q
What do geneticists study?
A
“Inheritance patterns of observable characteristics”
11
Q
Suitable organisms for genetic experiments
A
“Observable discontinuous features
12
Q
Examples of organisms used in genetic studies
A
“Bacteria
13
Q
Geneticist’s tool in the early twentieth century
A
“Fruitfly (Drosophila melanogaster)”
14
Q
Who made the fruitfly famous?
A
“Morgan”
15
Q
Why was the fruitfly used?
A
“Verify Mendel’s findings
16
Q
Adult fruitfly size
A
“0.5 cm”
17
Q
Where are fruitflies kept
A
“Laboratory in large numbers”
18
Q
How to distinguish male and female fruitflies
A
“Males: rounded abdomens
19
Q
Fruitfly life cycle
A
“Completes within two weeks”
20
Q
How many chromosomes do fruitflies have?
A
“Four homologous pairs”
21
Q
Fruitfly characteristics
A
“Many easily distinguishable discontinuous characteristics”
22
Q
What is a character?
A
“Distinct structural or functional feature”
23
Q
Other names for characters
A
“Traits or characteristics”
24
Q
What is heredity?
A
“Transmission of inherited characters from parent to offspring via genes”
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What is heredity responsible for?
"Similarity and variation between parents/offspring/individuals"
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Cause of similarity
"Genes inherited from parents"
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Cause of variation
"New combination of genes"
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Advantage of variation
"Increased chance of survival and reproduction if suited to environment"
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What kind of characters can be transmitted?
"Characters controlled by genes"
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Gene function
"Directs development of proteins"
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Protein function in heredity
"Leads to visible expression of the character"
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Example of gene action
"Gene for haemoglobin structure leads to red blood"
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What is genotype?
"Sum total of genes inherited from parents (genetic make-up)"
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What does genotype set?
"Limits within which characters can vary"
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Causes of inherited character variations
"Environment or use/disuse"
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Example of environmental effect on inherited character
"Skin color and sunlight exposure"
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What is phenotype?
"Actual physical expression of characters"
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What is phenotype due to?
"Interaction between genotype and environment"
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Are acquired modifications inherited?
"No"
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Why aren't acquired modifications inherited?
"They don't change gene structure (genotype)"
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What is a mutation?
"Change in gene structure (genotype)"
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When can a mutation be inherited?
"If it occurs in gametes
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What determines inherited characters?
"Genes"
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How many sets of chromosomes do diploid organisms have?
"Two (homologues)"
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How many copies of each gene do diploid organisms have?
"Two"
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Where are gene copies located?
"Identical loci on homologous chromosomes"
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How are gametes produced?
"Meiosis"
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Are gametes haploid or diploid?
"Haploid"
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How many copies of each gene in gametes?
"One"
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How are zygotes formed?
"Fusion of male and female gametes"
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Are zygotes haploid or diploid?
"Diploid"
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How many copies of each gene in zygotes?
"Two (one from each parent)"
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How are characters transmitted?
"Via gametes"
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Parent generation symbol
"P"
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First filial generation symbol
"F1"
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Sexual union/mating term
"Cross (x)"
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Alternative forms of a gene
"Alleles"
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Example of alleles
"Red and white flower color in pea plants"
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Allelic pair synonym
"Alleles"
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Cause of alleles
"Mutations"
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Number of genes passed on by parents
"Thousands"
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Character example for single-factor inheritance
"Flower color in pea plants"
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Alleles for pea plant flower color
"Red (R) and white (r)"
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What is breeding true?
"Stock producing same offspring when crossed among themselves"
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Genotype of pure stock of red-flowered pea plants
"RR"
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Genotype of pure stock of white-flowered pea plants
"rr"
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Allele composition of gametes from pure red-flowered pea plants
"Only R"
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Allele composition of gametes from pure white-flowered pea plants
"Only r"
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Genotype of zygotes from crossing pure red and white pea plants
"Rr"
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Homozygous definition
"Two copies of the gene controlling a character are identical"
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Examples of homozygous genotypes
"RR or rr"
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Monohybrid cross definition
"Cross involving alleles of one specific character"
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Parent genotypes in monohybrid cross
"RR x rr"
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F1 generation phenotype
"All red"
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F1 generation genotype
"Rr"
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Dominant form definition
"Form of character that is seen in the F1 generation"
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Recessive form definition
"Form of character that is masked in the F1 generation"
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Allele representation
"Dominant: uppercase letter
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Alleles in gametes from RR parent
"R"
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Alleles in gametes from rr parent
"r"
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Allele combination in F1 zygotes
"Rr"
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Why are F1 plants red?
"R allele (red) is dominant over r allele (white)"
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When does white flower color appear?
"Only in rr genotype (homozygous recessive)"
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Heterozygous definition
"Two copies of the gene controlling a character are different"
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Heterozygous genotype example
"Rr"
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Homozygous phenotype
"Red"
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Heterozygous phenotype
"Red"
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Hybrid synonym
"Heterozygous"
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F1 generation cross
"Self-pollination of Rr plants"
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F2 generation phenotype ratio
"3 red : 1 white"
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What does F2 ratio show?
"Heterozygotes don't breed true
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Gametes produced by F1 plants (Rr)
"R and r"
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Possible zygotes in F2 generation
"RR
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F2 generation phenotypes
"Red-flowered and white-flowered plants"
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F2 generation phenotypic ratio
"3:1 (red:white)"
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F2 generation genotypes
"RR
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F2 generation genotypic ratio
"1:2:1 (RR:Rr:rr)"
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Homozygous red-flowered genotypes
"RR"
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Heterozygous red-flowered genotypes
"Rr"
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How to determine the genotype of a red-flowered plant
"Test-cross (cross with recessive white-flowered plant or tester stock)"
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Offspring of RR x rr cross
"All red-flowered (Rr)"
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Offspring of Rr x rr cross
"Half red-flowered (Rr)
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Why use a recessive tester stock in a test-cross?
"Its genotype is identifiable by its phenotype"
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Human example of single-factor inheritance
"Tongue-rolling"
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Alleles for tongue-rolling
"T (dominant
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Genotypes of tongue-roller
"TT or Tt"
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Genotype of non-roller
"tt"
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Dihybrid cross definition
"Cross involving inheritance pattern of two characters"
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Characters in dihybrid cross example
"Seed color and seed shape in pea plants"
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Alleles for seed color
"Y (dominant
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Alleles for seed shape
"R (dominant
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Parent genotypes in dihybrid cross
"RRYY (round
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F1 generation genotype (dihybrid)
"RrYy (round
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Gametes produced by RRYY parent
"RY"
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Gametes produced by rryy parent
"ry"
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Allele distribution in dihybrid cross
"Independent assortment"
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Gametes produced by F1 generation (RrYy)
"RY
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F2 generation phenotypes (dihybrid)
"Round yellow
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F2 generation phenotypic ratio (dihybrid)
"9:3:3:1"
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F2 generation genotypes (dihybrid)
"9"
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Homozygous genotypes in F2 (dihybrid)
"4"
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Heterozygous genotypes in F2 (dihybrid)
"5"
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Who performed the first quantitative studies on inheritance?
"Gregor Mendel"
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When did Mendel publish his work?
"1867"
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Mendel's laws
"Law of Segregation and Law of Independent Assortment"
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Law of Segregation key points
"Genes are discrete units
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Law of Independent Assortment key point
"Alleles on different chromosomes assort independently during meiosis"
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Mendel's study organism
"Garden peas"
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Mendel's studied traits
"Seven discontinuous traits"
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Mendel's trait characteristics
"Two forms of expression (dominant and recessive)"
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Mendelian trait definition
"Character following Mendel's laws"
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Mendelian trait features
"One pair of alleles
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Mendel's first step
"Establish true breeding stocks by self-pollination"
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Mendel's second step
"Cross true breeding plants with alternative forms of a trait"
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Mendel's example cross
"Green pod x yellow pod"
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Mendel's pollination method
"Removed immature anthers
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Mendel's pollination prevention
"Covered pollinated flower with paper bag"
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Mendel's reciprocal cross
"Reversed pollen donor/recipient"
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Mendel's final step
"Self-pollinated F1 offspring to produce F2 generation"
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Mendel's data collection
"Counted number of each offspring type in F1 and F2 generations"
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Importance of Mendel's quantitative data
"Helped understand heredity principles"
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Albinism
"Condition with lack of pigment
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Cause of albinism
"Lack of melanin in the malpighian layer of the skin"
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Enzyme lacking in albinism
"Tryopsine"
145
Action of Tryopsine
"Synthesizes a pigment to form melanin"
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Gene causing albinism
"Recessive"
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Genotype of an albino
"aa"
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Genotype of a person with normal skin Colour
"AA"
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Genotype of a carrier for albino gene
"Aa"
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Genotype of a man that is a carrier for albinism gene married a woman of albinism
"Aa X aa"
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Sickle cell anaemia
"Inherited disease caused by abnormal shape of the red blood cell."
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How is abnormal red blood cell inherited?
"Indented from both parents by the offspring."
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Function of normal red blood cell
"transports Oxygen to different part of the baby with the help of haemoglobin."
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Function of abnormal red blood cell
"contains less haemoglobin and cannot transport Oxygen efficiently round the body."
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Shape of normal red blood cell
"spherical"
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Shape of abnormal red blood cell
"crescent or comma
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Gene for abnormal red blood cell
"S"
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Gene for normal red blood cell
"S"
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Dominance of normal red blood cell gene
"dominant over the gene for abnormal red blood cell"
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Genotype of a sickler
"SS"
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Genotype of a couple that are not sicklers to have a sickle cell baby
"Parents should be carriers (Ss)"
