1-mendelian genetics

Question 1

trait

Answer 1

any observable characteristic of an organism

Question 2

phenotype

Answer 2

state of the trait
determined by the interaction between genotype and environment

The observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.

Question 3

Gregor Johann Mendel

Answer 3

• scientist and Augustinian friar
• 1822-1884
• contemporary of Charles Darwin!! but never met
• known as the father of modern genetics
  
  • documented patterns of genetic inheritance before the discovery of genes, chromosomes, DNA, meiosis
• ✨fun fact ✨ started studying by mice, but it was inappropriate for a friar to study animal sex, so he switched to peas

Question 4

what did people believe about genetics before mendel’s discoveries?

Answer 4

• they thought phenotypes were inherited through “blending inheritance”
  
  • if black cat mates with white cat, then offspring should be shades of grey!

Question 5

why did mendel study peas??

Answer 5

• Grow and reproduce quickly
• easy to Maintain
• easily Identifiable traits/phenotypes
• easy to Cross (purposefully mate) parents
• fewer Ethical concerns
• it was a model organism!!

GMICE
Good
MICE (acronym)

Question 6

other model organisms bc why not

Answer 6

rockcress
mouse
fruit fly
bacteria
nematoda
yeast

Question 7

what mendel couldn’t have known at the time

Answer 7

• each trait only had two possible phenotypes (e.g., yellow of green)
• each trait was determined by 1 gene with only 2 alleles
• one allele was dominant over the other allele
• the genes were on separate chromosomes (not physically linked)
• the traits were autosomal (not X-linked)

Question 8

F generation stands for

Answer 8

F = filial generation

Question 9

Mendel’s process for breeding peas

Answer 9

mendel started with “true-breeding” (pure breeding) parents with same phenotypes
- round-seeded parent + round-seeded parent = all round-seeded offspring
- wrinkle-seeded parent + wrinkle-seeded parent = all wrinkle-seeded offspring

Mendel then crossed true-breeding parents with different phenotypes
- mendel crossed a true-breeding round-seeded parent with a true-breeding wrinkled-seeded parent
- offspring only had round seeds

then… allowed the F1 hybrids to self-pollinate!!
- when the F1 hybrid were allowed to self-pollinate, the wrinkled seeds reappeared!!!
- the F1 cross produced offspring (F2) that had phenotypic ratio of ~3:1

Mendel also performed reciprocal crosses to see if the sex of the parent affects the outcome
- same outcome (3:1 ratio) regardless of whether alleles come from male or female parent
- so… sex is not important, which indicates that the gene is on an autosome, not an X-chromosome

Question 10

monohybrid cross

Answer 10

genetic mix between two individuals who have homozygousgenotypes

Question 11

dominant and recessive meaning?

Answer 11

refers to relationships between specific alleles

• dominant allele: determines the phenotype of a heterozygous and homozygous dominant individual; codes for funcitonal protein
• recessive allele: phenotype is observed only in a homozygous recessive individual; typically codes for proteins that are non-function or have reduced function

Question 12

reciprocal cross

Answer 12

phenotypes of male and female are reversed in different crosses

Question 13

phenotypic ratio when crossing TWO HETEROZYGOUS TRAITS!

Answer 13

9:3:3:1

Question 14

who invented the punnett square

Answer 14

invented by Reginald Punnett, a geneticist (1875-1967)

Question 15

“And” probability rules

Answer 15

MULTIPLY probability

Question 16

“or” probability rules

Answer 16

ADD probabilities

Question 17

test cross

Answer 17

an individual with a known/unknown genotype is crossed with an individual that is homozygous recessive (test) for the genes under consideration

another use: determining the genotype of an individual with a dominant phenotype but unknown genotype

• if offspring all have the dominant phenotype:
  
  • unknown parent was likely homozygous dominant
• if some offspring have the recessive phentotype:
  
  • unknown parent is heterozygous