Chapter 14: Mendelian Inheritance

Question 1

Self-fertilization

Answer 1

• the male organ and female organ are on the same plant
• male organ provides female organ with sperm cells needed to provide its own fertilization; not needed from another plant
• will end up with identical offspring, no varying traits

Question 2

Cross-fertilization

Answer 2

• process where anther is cut off of a plant, and pollen from a different plant is transferred to them
• collect pollen from one individual and transfer it to the female organ of a flower on another plant, whose male organs have been removed

Question 3

hybrids

Answer 3

• result from crosses in fertilization between true-breeding parents

Question 4

Homozygous

Answer 4

Two dominant or two recessive alleles

Question 5

Heterozygous

Answer 5

One dominant and one recessive allele

Question 6

Dominant

Answer 6

more prevalent phenotype

In studies ALWAYS seen in F1 generation

3 to 1 in F2(3 dominant, 1 recessive expression)

Question 7

recessive

Answer 7

less prevalent phenotype

Question 8

Describe Mendel’s general experiment: What were the results?

Answer 8

• Takes true breeding varieties(parental generation)

If self-fertilized, the same characteristics will always appear

So Mendel Performs crosses between true-breeding parents to make hybrids(first filial generation – F1); then Mendel has Self-fertilized hybrids(second filial generation-F2)

This resulted in an F1 generation having all round seeds, and the F2 generations having round and wrinkled seeds in a 3:1 ratio

Question 9

What traits were studied in the Mendel Experiment?

Answer 9

shape, color, shape of pod, pod color, flower color, flower and pod position, and stem length

Question 10

How did Mendel’s experiment counteract previous conceptions of inheritance?

Answer 10

Mendel helped discover genes are not a blending inheritance of the two different parents of the offspring; they either show the trait or do not show the trait

Exceptions later on

Question 11

Describe Mendel’s general experiment: What were the results?

Answer 11

• Makes true breeding varieties(parental generation)

If self-fertilized, the same characteristics will always appear

So Mendel Performs crosses between true-breeding parents to make hybrids(first filial generation – F1); then Mendel has Self-fertilized hybrids(second filial generation-F2)

This resulted in an F1 generation having all round seeds, and the F2 generations having round and wrinkled seeds in a 3:1 ratio

ALL OF THE CROSSES IN HIS STUDIES YIELDED A 3:1 ratio (3 dominant traits shown to the 1 recessive trait shown)

Question 12

Particulate Inheritance

Answer 12

discrete units are inherited, not blended

Question 13

Genes

Answer 13

sequence of nucleotides in DNA(later used to transcribe RNA of sorts)

Question 14

Alleles

Answer 14

different versions of a gene

A singular allele would be presented as one letter

alleles are different versions of a gene (e.g. blue eyes vs brown eyes) that can be present at a gene locus (a gene’s location on a chromosome)
Example: Rr would have two alleles, an R allele and an r allele

Question 15

Genotype

Answer 15

genetic makeup; made up of two parents producing the offspring; total sum of alleles

Question 16

Phenotype

Answer 16

expressed characteristics that can be observed

Question 17

Genotype vs Phenotype

Answer 17

phenotype is seen, genotype is part of type of formula/set letters

Question 18

Punnet squares

Answer 18

Used (in Mendel experiments) to explain and predict genotypic and phenotypic ratios

Question 19

Explain setup of Mendel’s seed example through genotype and phenotype

Answer 19

R = dominant allele(Round)
r = recessive allele(wrinkled)

Genotypes possible
RR = homozygous dominant
Rr = heterozygous (dominant) - hybrid!!
rr = homozygous recessive

IMPORTANT TO LOOK BACK AT MEIOSIS HERE! Forming a zygote means it holds a copy of each gene

Question 20

Explain the interpretation of Mendel’s epxeriment in genotypic and phenotypic seed example

Answer 20

RR x rr: gives all Rr offspring(F1 generation)
* One trait disappears
* Genotype: heterozygous
* Phenotype: round seeds

F1 generation
* Rr x Rr
* Offspring genotype:
1 RR(homozygous dominant)
2 Rr(heterozygous)
1 rr (homozygous recessive)
Offspring phenotype: 3 round seeds, 1 wrinkled seed; Phenotype vs genotype ratios differ; Multiple traits for F2 generation produced; Trait reappears

DRAW Punnett square!!

Question 21

Mendel’s Law

Answer 21

Law of segregation: two different alleles segregate from each other during meiosis
(Ex: RR and rr separated into R & R, r & r)

during gamete formation, the segregation of one gene does not influence the segregation of another gene for a different trait

Note Separation of homologous chromosomes pairs in meiosis I!!

Question 22

What did Mendel’s studies lead to?

Answer 22

Chromosome Theory of Inheritance(found by someone else): Genes are located on chromosomes, each at a particular gene locus

This explains Mendel’s Principle of Segregation: the physical basis for the segregation of Mendel’s traits is the separation of alleles when homologous chromosomes pairs are separated in Meiosis I

REMEMBER EVEN IF THESE LAWS ARE CONNECTED TO MEIOSIS, THEY HAVE EXCEPTIONS TODAY

Question 23

Mendel’s Second Law

Answer 23

Independent Assortment:

Because two genes are usually located on separate chromosomes, they sort independently of each other during meiosis

Example: seed color and seed shape do not predict the other

Linked genes are just referring to genes on same chromosome

REMEMBER EVEN IF THESE LAWS ARE CONNECTED TO MEIOSIS, they HAVE EXCEPTIONS TODAY!

Question 24

Testcross

Answer 24

breeding the plants/organisms tests to determine unknown genotypes

HAS TO BE DONE an individual of dominant phenotype but unknown genotype (homozygous dominant or heterozygous) and with an individual of known recessive genotype AND phenotype

Creates 1:1 phenotypic and genotypic ratio!!