Unit 1 - Definitions Flashcards

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1
Q

DNA

A

hereditary material in humans & most living organisms

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2
Q

chromatin

A

complex of DNA and protein in eukaryotic cells

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3
Q

eukaryotic chromosome

A

linear molecule of DNA associated with histone proteins and packaged into higher order structures

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4
Q

telomere

A

stable ends of a linear chromosome

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5
Q

centromere

A

constricted region of chromosome where kinetochore forms and spindle microtubules attach during the cell division (sister chromatids held together by these too)

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6
Q

locus

A

position of a gene on a chromosome

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7
Q

haploid (n)

A

one set of Chromosomes

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8
Q

diploid (2n)

A

two sets of Chromosomes

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9
Q

non-homologous chromosomes

A

like XY sex chromosomes, have alleles on different genes.

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10
Q

autosomes vs sex chromosomes

A

chromosomes that are the same in M/F
vs
a pair of chromsomes that differ in M/F

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11
Q

homologous chromosomes

A

chromosome pairs of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci
- may show allelic variation at a locus

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12
Q

kinetochore

A

complex of proteins that assembles at the centromere and serves as site of mircotubule attachment during cell division

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13
Q

spindle microtubules

A

filaments responsible for moving chromosomes during cell division

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14
Q

sister chromatids

A

2 linear chromatids that are connected by a centromere, they will be genetically identical

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15
Q

meiosis vs fertilization

A

production of haploid gametes (n)
vs
restoration of the diploid state (2n) in the next generation

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16
Q

genotype

A

the complete genetic makeup of an individual organism.
- determines phenotype

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17
Q

phenotype

A

a measurable trait of an organism that is controlled by one or more genes but can be influenced by environmental effects.

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18
Q

dominant allele

A

an allele whose trait is expressed in heterozygous individuals (ex: RR, R_)

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19
Q

recessive allele

A

an allele whose trait is NOT expressed in heterozygous individuals (ex: rr)

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20
Q

monohybrid cross

A

a cross between parents that differ by a single trait (RR x rr)

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21
Q

dihybrid cross

A

a cross between parents that differ by two traits (RR YY x rr yy)

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22
Q

Probability

A

No. of times a particular event is expected to occur out of the total number of possible outcomes

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23
Q

product v sum rule

A

product rule
- joint events, multiply together probabilities

sum rule
- disjoint events, add together probabilities

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24
Q

wild type gene

A

the allele most often found in natural populations.
Often symbolized by one or more letters and a plus sign (+).

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25
Q

Allelic series

A

the set of >2 alleles that occur within a given natural
population.

26
Q

Complete dominance

A

The phenotype of the heterozygote is the same as the phenotype of one of the homozygotes.

27
Q

Biochemical basis of dominance

A

In a biochemical pathway, half the amount of “normal” protein is produced by the heterozygote compared to the dominant homozygote. When half the amount of the
“normal” protein is sufficient to obtain a given phenotype, the heterozygote is deemed haplosufficient (half # of copies is enough to give full phenotype)

28
Q

Incomplete (partial) dominance

A

The phenotype of the heterozygote is intermediate between phenotypes of the two homozygotes. The heterozygote phenotype may fall at any point within the range of the homozygotes.

29
Q

haploinsufficient vs haplosufficient

A

dominant phenotype in diploid organisms that are heterozygous for a loss-of-function allele

vs

a single copy of a functional gene is enough to maintain normal function.

30
Q

Codominance

A

The phenotype of the heterozygote simultaneously expresses the phenotype of both homozygotes. The phenotype of the heterozygote does NOT fall within the range of homozygous phenotypes.

31
Q

Dominance

A

an allele at one locus interferes with or prevents (hides) the expression of a gene at the same locus.

32
Q

Epistasis

A

an allele at one locus interferes with or prevents (hides) the expression of a gene at a different locus.

33
Q

Epistatic genes

A

can mask other loci and, at the same time, be dominant or recessive to alleles at their locus.

34
Q

Complementation

A

The expression of a wild type phenotype in an individual carrying two mutant alleles. This is an indication that the alleles are on different loci.

35
Q

event vs total group size

A

event
- “thing” we can see and count
- usually phenotypes sometimes genotypes

total group size
- total number of counts observed for all events

36
Q

P = n! / (x!) (y!) x (p^x) (q^y)

A

n = total group size (observations in all events = x+y)
x = number of times we observe event 1
y = number of times we observe event 2
p = probability of event 1
q = probability of event 2

37
Q

P = n! / (x!) (y!) (z!) (etc!) x (p^x) (q^y) (r^z) (etc)

A

n = total group size (x+y+z)
x = number of times we observe event 1
y = number of times we observe event 2
z = number of times we observe event 3
p = probability of event 1
q = probability of event 2
r = probability of event 3

38
Q

Sexual reproduction

A
  • alternation between haploid and diploid cell types (most eukaryotes)
  • process of organism reproduction that results in offspring that are genetically distinct from their parents
39
Q

Sex

A

the phenotype of sex; a classification system based on biological differences between males and females rooted in anatomy or physiology.

40
Q

Monoecious

A

the condition of having both male and female reproductive structures in the same organism

41
Q

Dioecious

A

species of organisms that have either male or female reproductive structures.

42
Q

Gender

A

a classification based on the social construction (and maintenance) of cultural distinctions between males and females. Gender refers to “a social construct regarding culture-bound conventions, roles, and behaviors for, as well as relations between and among, women and men, boys and girls” (Krieger, 2003).

43
Q

Genetic sex determination

A

sexual phenotype is determined by genes at one or more loci carried on autosomes. There are no sex chromosomes in this system

44
Q

Environmental sex determination

A

sexual phenotype is determined in part, or in full, by environmental factors

45
Q

primary sex characteristics

A
  • type of gamete that is made.
  • In humans, this is sperm vs. egg.
46
Q

secondary sex characteristics

A
  • traits that tend to differ between the sexes of a species, but which are not directly part of the reproductive system.
  • In humans, examples include height, bone density & structure, muscle mass, fat distribution, facial hair, voice, & some aspects of social behaviour
47
Q

dosage compensation and ex

A

mechanism that equalizes the amount of protein produced by X-linked genes between heterogametic and homogametic sexes.

ex:
males (XY): 1× gene products
females (XX): 2× gene products (double “dose” of X-linked genes)

48
Q

Bar body

A

a mostly inactivated X chromosome in females.

49
Q

Anhidrotic ectodermal dysplasia

A
  • Human X-linked trait characterized by several conditions including skin having no hair and no sweat glands.
  • Heterozygous women have irregular “patches” of affected skin.
50
Q

Linkage group

A

a collection of genes that do not assort independently into gametes because they are located on the same chromosome.

51
Q

Meiocyte

A

a diploid cell in which meiosis can take place

52
Q

Recombination

A

assortment of alleles into novel (non-parental) combinations

53
Q

Inter-chromosomal recombination & mechanism

A
  • assortment of alleles for genes on different chromosomes into novel combinations.
  • mechanism: random alignment of chromosome pairs (metaphase I) and segregation (anaphase I) in meiosis
54
Q

Intra-chromosomal recombination & mechanism

A
  • assortment of alleles for genes located on the same chromosome into novel combinations.
  • mechanism: exchange of DNA by crossing over (prophase I) in meiosis
55
Q

Genetic map

A

map of gene location on chromosomes obtained by using genetic recombination data

56
Q

Discontinuous (or qualitative) trait

A

a trait having only a few, distinct, phenotypes; often with a simple relationship to genotype (but not always).

57
Q

Polygenic trait

A

a trait determined by the affects of alleles at many different loci.

ex:
1. quantitative traits (continuous)
2. threshold traits (present or absent)
3. meristic traits (countable)

58
Q

mendelian vs quantitative traits

A

Arise from genes that have an effect large
enough for a recognizable discontinuity in
the presence of segregation at other loci
and non-genetic variation

vs

Arise from many genes with small effects
relative to segregation at other loci and
non-genetic variation

59
Q

Quantitative Genetics

A

the branch of genetics that uses statistical and analytical
procedures to understand how genes and environment influence continuous traits in groups of individuals, and study the inheritance of such traits.

60
Q

Quantitative Trait Loci (QTL)

A

a chromosome segment containing gene(s) (polygene)
that control a polygenic trait