Chapter 12: Genes, Chromosomes, and Heredity Flashcards

(49 cards)

1
Q

what is another name for homologous chromosomes?

A

Homologs

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2
Q

What are homologs/ homologous chromosomes?

A

-Homologous pairs
-look the same but have different information
-#1-22 are SOMATIC/ AUTOSOMAL chromosomes (NON-SEX CHRMS)
-# 23 is SEX CHROMOSOMES (X or Y)
22 pairs of autosomal; 1 pair sex

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3
Q

What is a Locus?

A

The spot on a chromosome where the gene is

-each gene resides on a certain locus/location on the chromosome

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4
Q

What is an Allele?

A

The different forms or variations of an instruction/gene

-ex: Allele for blue/ green eye color

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5
Q

Can homologous chromosomes have the same gene at the same locus but have different alleles?

A

YES

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6
Q

Difference between Homozygous and Heterozygous

A

Homo: alleles are the SAME (HH or hh)
Hetero: alleles are DIFFERENT (Hh)

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7
Q

Traits of a Dominant Allele

A
  • The allele that is expressed
  • May mask or suppress recessive allele
  • Written in UPPERcase (H)
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8
Q

Traits of a Recessive allele

A
  • Allele that is present but NOT expressed
  • Masked or Suppressed by dominant allele
  • Written LOWER case (h)
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9
Q

What is a Genotype?

A

Genes an organism or person has

EX: HH, Hh, hh

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10
Q

What is a Phenotype?

A

Expression of those genes; PHYSICAL expression

EX: Hairline (HH), Receded hairline (hh)

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11
Q

What do Mendelian Genetics have to do with?

A

How heredity is the expression of genes that are passed on an INHERITED

  • not that you are a mix of your parents but a have component(s) of each
  • Law of Independent Assortment and Law of Segregation
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12
Q

Example of a Shorthand Representation of Genotype

A

H (letter for gene) with line under it

  • the line/bar represents the chromosome
  • The letter represents the allele or specific locus
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13
Q

What is a monohybrid cross?

A

Parental Genotypes -> Gamete Genotypes -> Offspring Genotypes

  • the probability of traits that the offspring will end up with
  • CROSS between two organisms with two genetic variations at the same parts of the locus
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14
Q

The Punnett Sqaure

A

Egg on one side; sperm on the other

Helps find each possible combination and the percentage of them

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15
Q

What is the Dihybrid Cross with UNLINKED loci?

A
  • Involves 2 loci
  • unlinked means on DIFFERENT Chromosomes
  • NOT TWO TRAITS; mulitple loci can contribute to a single trait
  • takes the parental genotypes (egg and sperms) and makes gamete genotypes
  • EX: Parental: Hh and Pp X Hh and Pp; makes 8 different combinations (4 from each) and 16 total
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16
Q

Describe Dihybrid Cross with LINKED loci

A

-involves TWO loci NOT two traits
-mulitple loci can contribute to a single trait
- on the SAME chromosome
EX: Parental to Gametes (same as before) but only one chrsm; HP/hp X HP/hp (4 diff combos)

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17
Q

Examples of Gene Interaction (8 of them)

A

Incomplete Dominance, Codominance, Pedigree Analysis, Polygeneic Inheritance, Pleotropy, EPISTASIS, Penetrance, and Expressivity

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18
Q

Explain Incomplete Dominance

A

The dominant allele NOT fully expressed

EX: Hair color Bb= tan hair; mix of both (NOT ONE OR THE OTHER basically)

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19
Q

Explain Codominance

A

When BOTH alleles are expressed with TWO different phenotypes
EX: ABO blood types (P^A P^A or P^B P^B or pp etc)
The P represents the locus

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20
Q

Explain Pedigree Analysis

A

Tracking genetic traits through several generations

-EX: gives the phenotypes of offspring, makes you figure out the parents Genotypes from it

21
Q

Familial Hypercholestremia

22
Q

Explain Polygenic Inheritance

A

The inheritance bases on 2 or more loci that influence a Single trait
EX: skin color and height (more pigmentation= taller; less pigmentation=shorter)
-Locus 1 + 2 + 3 = Trait 1

23
Q

Explain Pleiotropy

A

A SINGLE locus affecting MULITPLE traits

24
Q

Examples of Pleiotropy

A

1) Pigmentation in mulitple body parts
- Pigmentation Gene -> Hair color, eye color, skin color
2) Marfan Syndrome: defect in gene for fibrillin-1 (important for structural organization of connective tissues)
- can affect thinness, limb elongation, hypermobile joints, lens dislocation, increased susceptibility to heart disease; basically tall weird looking man

25
Explain Epistasis
- GENES CONTROLLING GENES - The expression of one gene is affected by another - Gene at one locus/location alters how the other one at a different locus expresses/shows the trait - NOT TWO TRAITS; TWO DIFF GENES
26
Bombay Factor
27
What is Penetrance?
The proportion of individuals in a group with a given genotype that actually SHOW the associated phenotype EX: Huntington's Disease - Dominant trait (H) - causes: Loss of neurons in brain, debilitation and early death, only 5% of people that have it do not express it, 95% express it (SO 95% PENETRANCE)
28
What is Expressivity?
The degree to which a genotype is expressed in an individual -if expression is detrimental, the disease is severe - EX: Polydactylism; having extra digits (fingers/toes) Expressivity has to do with how much of it is seen or expressed; is it one hand or both, on feet and hands, one extra digit or mulitple???
29
What can determine phenotypes?
GENES AND ENVIRONMENT | -Nutrition, pH, Light, etc
30
Rule for Dihybrid Crosses
- Hybrid X Hybrid | - always a 3:1 OR 75:25 phenotypic ratio
31
How do we inherit alleles?
We inherit TWO alleles | -ONE from EACH parent
32
Law of Segregaition
The two alleles SERGREGATE in meiosis and end up in different gametes - so PP and pp will each go into different, unique sex cells (PP can only donate P and pp can only donate p) - thats how each gamete made in meiosis is different
33
What is a Punnett sqaure used for
A diagram to PREDICT the results of a genetic cross between two organisms -possible combinations of egg and sperm
34
True breeding
Homozygous is considred to be TRUE (same genotypes) | Heterozygous is not TRUE its a HYDRID (two diff)
35
Do an organisims traits reveal its genetic makeup?
NOOO PHENO VS GENOTYPES (i can tell you have blonde hair, but idk wtf you got from your parents or what they look like)
36
Cross between heterozygotes for ONE trait?
Monohybrids
37
Dihybrid Cross
Cross between TWO traits - will be hetero for both traits (DI (two) hydrids together) - to see if traits depend on each other (Tall and White or short and black?) - bigger punnett square
38
Ratio for Double Hetero cross in a Dihybrid? (Independent Assortment)
9:3:3:1
39
Dihybrid cross example
Crossing two heterozygous : YyRr x YyRr - separate them first - Yy x Yy and Rr x Rr - Multiply each probability by each other to find total - Probability of YYRR = 1/4 YY x 1/4 RR = 1/16 chance - Probability of YyRr = 1/2 Yy x 1/2 Rr = 1/8 chance
40
Degrees of Dominance (3 of dem)
Complete: When phenotypes of the heterozygote and dominant homozygote are identical (dominant wins and shows) Incomplete: when the phenotypes is somewhere between the two hydrids (mix; red + white = pink); IN-between - lightskins are incomplete dominance lol Codominance: Two dominant alleles affect the phenotypes in different ways (both show; black + white = black with white spots)
41
Are dominant alleles more common than recessive alleles in populations?
NAUR - dominant alleles can be rare - ex: the polydactyly (extra digits) is 1 out of 400 and it is a dominant trait
42
What is it called when genes have multiple phenotypic effects?
Pleiotropy
43
Example of Epistasis
Labrador Retrievers - the coat color depends on TWO genes - One gene determines the pigment color (Alleles for Black B and alleles for brown b) - The SECOND gene (alleles C for color and c for NO color); determines whether the pigment will be shown in the hair
44
example of polygenic inheritance
Skin color: Different variations -can be white with yellow undertone or white with pink undertone, etc Large spectrum/ variations
45
When is the Phenotypic range (options for what you will look like) the broadest?
When there are multiple genes/ polygenic characters | -the genes are effected by environment and genetics
46
Are humans good for genetic research?
NO not really lol - they take too long to make (9 months) - Don't have enough offspring (bc it freaking sucks being preggo) - it's unethical to breed and study the babies - a lot of mendelian research on plants can be applied so that's why we use animals or plants mostly
47
What can you use pedigree analysis for?
To trace ancestry and see what the offspring will have/ not have - ex: will the baby have a big nose because their grandparents did/didn't? - used a lot for healthcare reasons - the squares and circles (filled or not filled in indicates mutation)
48
If a trait isn't in the parents but the child has it, is it dominant or recessive
RECESSIVE - the trait was hidden until it reappeared in the kid - someone in the family somewhere had it
49
What are carriers?
When they pass on a recessive allele but don't have/show it - ex: Mom Rr -> Child rr (has mutation) - so the mom and dad are carriers