Genetics (Part A - Mendel) Flashcards

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1
Q

what are genetics

A

-deals with the way biological characteristics are inherited
-involves sexual reproduction (meiosis)
-genes of an organ

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2
Q

how many genes are in the human genome

A

20,000-25,000

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3
Q

are humans identical

A

identical in 99.9% of gene sequences

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4
Q

where are genes located

A

on chromosomes

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5
Q

what info do genes contain

A

contains info needed to produce a specific protein

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6
Q

what are alleles

A

different version of the same gene

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7
Q

where are alleles located

A

on the same loci of homologous chromosomes

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8
Q

what is a locus

A

place where a gene is on a chromosome

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9
Q

what are the characteristics of a homologous pair

A

similar size
same number of genes
same genes at the same space

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10
Q

what is a dominant allele

A

allele that masks the presence of another allele (uppercase letter)

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11
Q

what is a recessive allele

A

allele that can be masked by the presence of a dominant allele (lowercase letter)

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12
Q

what is BB called

A

homozygous dominant

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13
Q

what is Bb

A

heterozygous

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14
Q

what is bb

A

homozygous recessive

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15
Q

does the allele being dominant have any effect on how common it is

A

no

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16
Q

what is a genotype

A

the combination of alleles (ex. BB, Bb, bb)

17
Q

what is a phenotype

A

the appearance of the characteristic (ex. purple or white)

18
Q

does knowing the phenotype give us the genotype

A

no because of heterozygous allele combination

19
Q

how do recessively inherited disorders occur

A

when the individual is homozygous recessive only

20
Q

what is a carrier

A

someone who carries the recessive gene but displays the dominant phenotype

21
Q

does the carrier of a disease have that disease

A

no

22
Q

how do dominantly inherited disorders occur

A

when the individual is homozygous dominant or heterozygous

23
Q

are Ff a carrier in a dominant disorder

A

no because they display the disease

24
Q

when crossing homozygous parents (one dominant one recessive) what is the outcome

A

all offsprings will display the dominant phenotype but carry the recessive gene

25
Q

when crossing two carriers with each other what is the outcome

A

75% will display the dominant phenotype
25% will display the recessive phenotype

26
Q

what is the law of segregation

A

both alleles will always end up in different gametes after meiosis

27
Q

what is a monohybrid cross

A

cross between two heterozygous individuals at one locus

28
Q

what is the purpose of a punnett square

A

determines the probability of an offspring having a particular genotype

29
Q

do the punnett square give us the for sure result to be expected

A

no
everything is random so this would only be the expected results from a large scale study

30
Q

what are the two rules of probability

A

addition rule
multiplication rule

31
Q

what is the addition rule

A

“or”
chances of having a boy or a girl
0.5 + 0.5 = 1

32
Q

what is the multiplication rule

A

“and”
chances of having a girl and a girl
(0.5)(0.5) = 0.25

33
Q

what is a test cross and what is it used for

A

cross done with a recessive individual to test whether an organism with a dominant phenotype is heterozygous or homozygous dominant

34
Q

what is a dihybrid cross

A

cross with alleles on two different loci (2 genes on different chromosomes)

35
Q

how do you know how many different combinations of alleles there are

A

2^n where n is the number of heterozygous alleles
AaBBccDe = 2^2 = 4

36
Q

how do you know how many combinations of gametes a parent can have (dihybrid cross)

A

foil the two genes
(Bb)(Ss) = BS Bs, bS, bs

37
Q

what is the ratio for dihybrid crosses and what is it called

A

phenotypic ratio
9:3:3:1 (most dominant to least)

38
Q

what is test cross

A

a cross with a recessive individual can be used to test whether an organism with a dominant phenotype is homzygous or heterozygous