Lesson 5: Mendelian Genetics

Question 1

what is a trait

Answer 1

a particular version of an inherited characteristic

Question 2

examples of traits

Answer 2

features like a persons eye colour, the shape of the leaf, colour of a flower, colour of a pea, etc.

Question 3

what was the past belief of how traits were inherited?

Answer 3

it was assumed that traits were a blend from the two parents (ex: black bird and white bird makes grey bird)

Question 4

who is gregory mendel and what did he discover/do

Answer 4

he was a monk and a biologist, and he was one of the first successful scientists to answer the question of how traits are inherited
- he conducted a series of experiments with garden peas

Question 5

what type of experiments did mendel conduct + whyd he pick that specific species

Answer 5

experiments with garden peas- chosen because it reproduces quickly and it was easy to control which parents produce offspring

Question 6

the pea plants have both male and female reproductive organs, so, the peas can either..

Answer 6

• self fertilize (self-pollinate)
• cross-fertilize (mate with others)

Question 7

what are true breeding plants, what happens when they reproduce by self pollination/sexual reproduction, and give an example

Answer 7

plants in which their offspring will have the same traits
- when these plants reproduce by self pollination or sexual reproduction with ANOTHER true breeding plant, the offspring produced will have the same traits
EX: purple flower true breeding plant will produce only purple flower offspring

Question 8

what are hybrid plants

Answer 8

the offspring of two different true-breeding plants

Question 9

what are crosses, and why did mendel do these processes?

Answer 9

crosses are controlled experiments- he did them to test how these traits were inherited through the use of true breeding and hybrid pea plants

Question 10

in mendels experiements, what had to happen in order for plants not to self pollinate?

Answer 10

the male reproductive organs (the anther) was removed to prevent self-pollination

Question 11

what is the generation of two true breeding plants called

Answer 11

parental (P) generation

Question 12

what is the generation of hybrid offspring called?

Answer 12

filial (F1) generation

Question 13

a new generation created from the F1 generation (with mixed traits) is called what + what is it a result of?

Answer 13

called the F2 generation- its a result of a MONOHYBRID CROSS

Question 14

what are some information we can determine about traits based off mendel’s experiments?

Answer 14

• the F1 generation always resulted in purple flowers even though they had one white and one purple flower parent
• this didnt fit the “blending” hypothesis from the past
• this showed that one trait was masking the other (purple masked white)

Question 15

what happened with the traits in the F2 generation? what ratio did it have and based off these results, what did mendel come up with?

Answer 15

the white flower trait reappeared
- the F2 generation consistently had a 3:1 purple to white flower ratio
- from these results, mendel came up with the first law of mendelian inheritance + the law of segregation

Question 16

first law of mendelian inheritance (what did mendel conclude of how traits were passed on)

Answer 16

mendel concluded that traits must be passed on by discrete heredity units which he called factors
- he hypothesized that even if factors are not expressed in an individual, they may still be passed on

Question 17

what are the different factors (in F1 generation)

Answer 17

• dominant factor (factor that is expressed)
• recessive factor (factor that remained, but was hidden)

Question 18

what are alleles and what role does it play in homozygous and heterozygous

Answer 18

alternate version of genes
- if both of your alleles are identical you are homozygous
- if your two alleles are different you are heterozygous

Question 19

what are the types of alleles

Answer 19

• dominant alleles
• recessive alleles

Question 20

how are dominant alleles and recessive alleles represented with (letter wise)

Answer 20

dominant= uppercase letter
recessive= lowercase letter

Question 21

what exactly does dominance mean in alleles

Answer 21

refers to which gene is EXPRESSED if two different alleles are present
- it doesnt have anything to do with a gene being better, more common, or stronger

Question 22

mendel’s law of segregation (what did the law of segregation hypothesize and what does it state)

Answer 22

the law of segregation was used to hypothesize why the 3:1 ratio was present in the F2 generation

this law states:
- each organism carries two factors (genes) one from each parent for each characteristic
- parent organisms donate only one copy of each gene in their gametes
(^this was long before we had any knowledge of the chromosome)

Question 23

genotype vs phenotype (what are both and how do they differ + provide examples of each)

Answer 23

the phenotype is the trait of an individual which is expressed
EX: a pea plant may have a purple flower or tall stem phenotype

the genotype is the individual genes an individual presents
- you cant determine this in all cases by what it looks like
EX: if you have purple flowers you are not certain if the genotype is Pp or PP

Question 24

how do we predict inheritance of alleles

Answer 24

we can study and predict the possible genotypes of offspring by the use of punnett squares
- it is a grid system where parent 1 and 2 alleles are shown and it shows the possible genotypes of offspring

Question 25

practice lots of scenarios and questions