Genetics Intro

Question 1

Genotype

Answer 1

• type of genes you have

Question 2

Phenotype

Answer 2

• result of the expression of those genes

Question 3

Blood Types

Answer 3

1. Type A- could have 2 copies of genes that code for A, AA or AO (A dominant)
2. Type B- BB or BO
3. Type AB- AB only, expresses both A and B
4. Type O- OO (homogenous recessive)

Question 4

blood markers

Answer 4

• there are markers on red blood cells for A and B
• no markers for O
• for AB, codominant, have both markers

Question 5

RH Factor

Answer 5

• negative and positive in blood type
• Codes for an enzyme that adds to another marker on cells
• If you have gene for enzyme that has RH factor–> then considered RH positive
• makes a difference in blood transfusions
• 2 alleles (+ and -)

Question 6

Rhogam

Answer 6

• substance that is injected into mothers before birth if they have -RH factor and baby is +RH
• during birth, antibodies can cross barrier (cells will not)–> this attacks blood cells of baby
• Rhogam blocks antibodies
• if antibodies are not blocked–> Creates RH disease–> presence of immature red blood cells in fetus (eyrthroblastosis- still have a nucleus), can cause baby to die

Question 7

Sickle cell anemia

Answer 7

• Change in amino acid makes a big difference in protein
• Glutamic acid (charged) is switched to valine (not charged) in position 6 from N terminus
• Causes hemoglobin to stick together in a funny way
• causes sickle cell shape–> sticky, get stuck in capillaries, cause pain in joints/organs
• Heterozygous- don’t have symptoms, but if two have child who is homozygous
• 2b = normal
• 1b 1s = asymptomatic, have the trait, resist malaria
• 2s = have the disease
  positive selection–> African American population has a higher concentration of sickle cell allele (resist malaria)

Question 8

hydroxy urea

Answer 8

• drug helps alleviate sickle cell disease
• During embryonic development, people can express fetal hemoglobin gene (F gene)- think it has a higher oxygen affinity (works better in fetal condition)
• this gene is turned off in adult and only hemoglobin A is expressed
• IN SICKLE CELL- patients have defective hemoglobin S that causes sickle cell–> drug can induce hemoglobin F (but there are side effects)

Question 9

Karyotype

Answer 9

• chromosomal analysis
• Can digitally arrange all chromosomes
• See if you have right numbers and sizes

Question 10

Genetics

Answer 10

• Involved in passing genetic information from one generation to the next

Question 11

heterochromia

Answer 11

• 2 different colored eyes

Question 12

the homunculus

Answer 12

• People thought there were tiny babies in sperm

Question 13

Plant parts

Answer 13

• flowers with both male and female parts
• pistil (middle part)- have female parts, egg is in the bottom of it
• stamen- male part
• Pollen is distributed to other things (animals)
• sexual reproduction- When pollen flies through air and into stigma–> goes down to egg

Question 14

Mendel

Answer 14

• Controlled which flower was fertilized by which stamen (pollen)
• Studied 7 different traits: flower color, seed color, seed shape, pod color, pod shape, flower position, plant height

Question 15

genetic protocol (Mendel)

Answer 15

• Parent 1 and parent 2
• F1= Cross parents and get offspring (1st filial generation)
• Self cross F1- mate w/ self, F2 = 2nd filial generation
• in F1, get dominant and same phenotype
• when you self cross in F2 ratio of traits that are dominant to recessive is 3:1

Question 16

carrier

Answer 16

• individuals that are heterozygous and showing dominant phenotype
• also have the “trait” for something

Question 17

autosomes

Answer 17

• regular chromosomes (not sex chromosomes)

Question 18

albinism

Answer 18

• autosomal recessive
• don’t make normal pigment
• eye red, no pigment so see blood color
• sometimes have vision problems
• Leucistic- have pigment in eyes, lack pigment in other areas

Question 19

Huntington’s Disease

Answer 19

• dominant neurodegenerative disease
• age 44, start experiencing shaking, chorea= a dance
• Huntington’s is rare, and rate is not increasing

Question 20

Frequency of a dominant allele

Answer 20

• has nothing to do with it being dominant
• Depends on whether it has been selected for or not
• ex. Huntington’s is dominant but rare

Question 21

test cross

Answer 21

• used to reveal the unknown genotype of an individual
• ex. if you don’t know if smooth is heterozygous or homozygous dominant
• cross with homozygous recessive
• -> if all dominant offspring–> know was homozygous dominant
• -> if 1:1 ratio–> know was heterozygous dominant

Question 22

dihybrid cross

Answer 22

• Each of these genes is sorting independently–> not affecting distribution of the other
• ratio is 9:3:3:1

Question 23

dihybrid test cross

Answer 23

• cross with homozygous recessive for both genes

- get ratio 1:1:1:1

Question 24

Mendel’s laws

Answer 24

1. Mendel’s 1st law = law of segregation- recessive gene exists separately from the dominant gene and reexpress in later generations
2. Mendel’s 2nd law = law of independent assortment- 2 different genes distribute themselves independently (9:3:3:1 ratio)

Question 25

Phenotypes/genotypes expected in offspring from a cross showing independent assortment

Answer 25

n = number of gene pairs being followed Monohybrid cross: 2^n = 2^1 = 2 ``` Dihybrid cross: Phenotypes 2^n = 2^2 = 4 Genotypes 3^n = 3^2 = 9 ``` Trihybrid cross: Phenotypes 2^n = 2^3 = 8 3^n = 3^3 = 27

Question 26

ratios to memorize

Answer 26

- Monohybrid cross 3:1 - Monohybrid test cross 1:1 - Dihybrid cross 9:3:3:1 - Dihybrid test cross 1:1:1:1