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Biology Exam 3 > Chapter 12: Genes, Chromosomes, and Heredity > Flashcards

Chapter 12: Genes, Chromosomes, and Heredity Flashcards

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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

A
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
Q

Explain Epistasis

A
  • 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
Q

Bombay Factor

A
27
Q

What is Penetrance?

A

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
Q

What is Expressivity?

A

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
Q

What can determine phenotypes?

A

GENES AND ENVIRONMENT

-Nutrition, pH, Light, etc

30
Q

Rule for Dihybrid Crosses

A
  • Hybrid X Hybrid

- always a 3:1 OR 75:25 phenotypic ratio

31
Q

How do we inherit alleles?

A

We inherit TWO alleles

-ONE from EACH parent

32
Q

Law of Segregaition

A

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
Q

What is a Punnett sqaure used for

A

A diagram to PREDICT the results of a genetic cross between two organisms
-possible combinations of egg and sperm

34
Q

True breeding

A

Homozygous is considred to be TRUE (same genotypes)

Heterozygous is not TRUE its a HYDRID (two diff)

35
Q

Do an organisims traits reveal its genetic makeup?

A

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
Q

Cross between heterozygotes for ONE trait?

A

Monohybrids

37
Q

Dihybrid Cross

A

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
Q

Ratio for Double Hetero cross in a Dihybrid? (Independent Assortment)

A

9:3:3:1

39
Q

Dihybrid cross example

A

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
Q

Degrees of Dominance (3 of dem)

A

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
Q

Are dominant alleles more common than recessive alleles in populations?

A

NAUR

  • dominant alleles can be rare
  • ex: the polydactyly (extra digits) is 1 out of 400 and it is a dominant trait
42
Q

What is it called when genes have multiple phenotypic effects?

A

Pleiotropy

43
Q

Example of Epistasis

A

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
Q

example of polygenic inheritance

A

Skin color: Different variations
-can be white with yellow undertone or white with pink undertone, etc
Large spectrum/ variations

45
Q

When is the Phenotypic range (options for what you will look like) the broadest?

A

When there are multiple genes/ polygenic characters

-the genes are effected by environment and genetics

46
Q

Are humans good for genetic research?

A

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
Q

What can you use pedigree analysis for?

A

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
Q

If a trait isn’t in the parents but the child has it, is it dominant or recessive

A

RECESSIVE

  • the trait was hidden until it reappeared in the kid
  • someone in the family somewhere had it
49
Q

What are carriers?

A

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

Biology Exam 3 (4 decks)

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