Genetics Flashcards

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1
Q

ploidy level

A

the number of chromosome sets that a cell carries Eg haploid 23, diploid 46

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2
Q

homogametic sex

A

individuals with two of the same sex chromosomes

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3
Q

heterogametic sex

A

individuals with two different sex chromosomes

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4
Q

somatic cells

A

all cells in the body of an organism apart form the sex cells (gametes)

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5
Q

germ cells

A

cells that give rise to gametes

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6
Q

meiosis type of division

A

reduction division (number of chromosomes becomes halved)

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7
Q

synapsis

A

when the maternal and paternal homologous pairs of chromosomes pair up

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8
Q

chiasma (chiasmata)

A

the point on the chromosome where crossing over occurs (the chromosome breaks)

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9
Q

recombinant chromatids/chromosomes

A

chromatids that have had crossing over occur to them (they have a new combination of alleles)

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10
Q

non-recombinant chromatids/chromosomes

A

chromatids that have not had crossing over occur to them 9have had no change in their alleles)

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11
Q

formula for number of possible chromosome pairs from independent assortment

A

2^n where n=the haploid number of the organism

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12
Q

when are chromosomes most visible

A

at metaphase

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13
Q

genotype

A

the set of alleles present in the DNA of an individual organism

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14
Q

homozygote

A

an individual with the homozygous genotype

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15
Q

heterozygote

A

an individual with the heterozygous genotype

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16
Q

Hemizygous

A

used to refer to males when talking about X-linked genes. Can be hemizygous dominant/recessive

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17
Q

phenotype

A

the physical representation of the genotype of an individual

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18
Q

complete dominance

A

where one allele is dominant over the other so the heterozygous individuals express the dominant trait only

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19
Q

incomplete dominance

A

when neither allele is dominant over the other so an intermediary or blended phenotype occurs in heterozygous individuals

20
Q

codominance

A

when both alleles are equally expressed in the heterozygous individual therefore no phenotype of fully dominant

21
Q

epigenetics

A

different environment causes methyl groups to attach to the cytosine bases of the DNA, however the DNA remains unchanged

22
Q

environmental influencers

A

DNA is unchanged but the environment changes the way these genes are expressed Eg chemically

23
Q

reprogramming

A

when epigenetic markers are erased during meiosis

24
Q

genetic cross

A

the deliberate mating of two organisms to determine the inheritance pattern of particular traits

25
Q

monohybrid cross

A

a cross following one trait in an organism (same gene at the same locus)

26
Q

dihybrid cross

A

tracking two traits in an organism (tow different genes at two respective loci)

27
Q

non-linked traits

A

traits that are inherited independently of one another as they are on separate chromosomes

28
Q

linked genes

A

genes that are inherited together as they are found on the same chromosome, known as linkage.

29
Q

HhKk + HhKk expected ration

A

9:3:3:1

30
Q

HhKk + hhkk expected ratio

A

1:1:1:1

31
Q

fixation

A

when an allele dominates a whole population

32
Q

trisomy

A

when there is an extra copy of a chromosome

33
Q

monosomy

A

when there is only one copy of a chromosome

34
Q

down syndrome: abnormality

A

trisomy 21

35
Q

down syndrome: symptoms

A

intellectual disability
developmental delays

36
Q

Klinefelter syndrome: abnormality

A

two x chromosomes and one y

37
Q

Klinefelter syndrome: symptoms

A

low testosterone
reduced male characteristics

38
Q

Turner syndrome: abnormality

A

missing an X chromosome, have 1 X chromosome

39
Q

Turner syndrome: Symptoms

A

short stature
infertile

40
Q

triplets/codons

A

DNA is divided into sets of three nucleotide segments which code for amino acids that when join form a protein

41
Q

aneuploidy

A

an abnormal haploid number of chromosomes

42
Q

test cross

A

used to find an unknown genotype by crossing an individual with the dominant phenotype with a homozygous recessive individual. Type of monohybrid cross.

43
Q

histone

A

proteins that the DNA wraps around

44
Q

genome

A

all the genetic information in a haploid set of chromosomes this can also be used on a larger scale with reference. For example the genome of the cell or person

45
Q

Nucleosome

A

8 histones wrapped in DNA

46
Q

chromatin

A

multiple nucleosomes, which makes up Chromosomes