Mendelian of Transmission Genetics

Question 1

Transmission Genetics

Answer 1

deals with how genes are transferred from parents to offspring

Question 2

Genes

Answer 2

basic physical units of heredity

Question 3

Reasons for Mendel’s Success

Answer 3

1. Choice of organism (easy to grow and to artificially hybridize)
2. Each experiment involves examination of one or very few pairs of contrasting traits
3. Accurate quantitative records

Question 4

Choice of organism (easy to grow and to artificially hybridize)

Answer 4

allowed the plant to fertilize in the lab

Question 5

Each experiment involves examination of one or very few pairs of contrasting traits

Answer 5

pea plant = one character and for that character there are contrasting traits

Question 6

Accurate quantitative records

Answer 6

1st time numerical data is emphasized here (also application of statistics); there is a need to have numerical data

Question 7

In what aspect is it quite important to highlight the reasons for Mendel’s success?

Answer 7

In the experimental design or the method that he used.

Question 8

Characters/Characteristics

Answer 8

• 7 visible features looked into by Mendel

- with two contrasting traits or forms

Question 9

Contrasting traits

Answer 9

Means there is quite an obvious distinction

Question 10

Constriction

Answer 10

narrow portions

Question 11

Axial/Terminal

Answer 11

at the end of the stem; the axis has an angle

Question 12

Monohybrid Cross

Answer 12

• 1 character/characteristics
• [automatically] includes one pair of contrasting traits
• two parents (true-breeding) each with one of the contrasting traits are mated
• tall plant (with two factors of tall) and dwarf plant (with two factors for Dwarf), both possess a pair of like unit factors; Gametes of Tall plant (1 factor for Tall) and Gametes of Dwarf plant (1 factor for Dwarf)

Question 13

What does the monohybrid cross automatically including 1 pair of contrasting traits suggest?

Answer 13

It suggests that we only focus on one character/characteristic.

Question 14

True-breeding

Answer 14

That particular plant can produce the same trait (or character) from one generation to the next

Question 15

P1

Answer 15

• Parental generation

- original parents

Question 16

F1

Answer 16

• first filial generation

- offspring of P1

Question 17

F2

Answer 17

• second filial generation
• offspring of F1
• result from selfing or self-fertilization

Question 18

Selfing/Self-fertilization

Answer 18

The individual itself can undergo fertilization

Question 19

Principles or Postulates of Inheritance by Mendel

Answer 19

1. Unit Factors in Pairs
2. Dominance/Recessiveness
3. Segregation

Question 20

Unit Factors in Pairs

Answer 20

• can be seen in all diagrams

- Unit Factors (occurs in pairs in an individual) control genetic characters

Question 21

What does the individual refer to?

Answer 21

Referring to a single organism (e.g. one human being, one pea plant, one earthworm)

Question 22

Unit Factor example

Answer 22

An individual receives one factor from each parent; Factors exist in pairs, so 3 combinations are possible: 2 factors for Tall, 2 factors for Dwarf, and 1 factor for each; so each individual have one of these combinations.

Question 23

What does it mean when unit factors control genetic characters?

Answer 23

Unit factors will give you a particular character.

Question 24

Dominance/Recessiveness

Answer 24

• applied when unit factors combine
• if 2 unlike/contrasting unit factors are present in an individual, one will be dominant while the other is recessive
• bottomline of the concept: if both dominant and recessive are received in the individual, you will only see the dominant trait (e.g. Tt genotype - the stem would be tall)

Question 25

Dominant unit factor

Answer 25

Controls the expressed trait

Question 26

Recessive unit factor

Answer 26

Controls the trait not expressed

Question 27

What does it mean when recessive controls the trait not expressed?

Answer 27

The organism has this but it is not visible (e.g. a pea plant having tall stem that is dominant and dwarf is recessive).

Question 28

Dominance/Recessiveness Example

Answer 28

Tall Stem (Dominant)
Dwarf Stem (Recessive)

Question 29

Segregation

Answer 29

• applies when it comes to RANDOM FERTILIZATION
• paired unit factors separate or segregate randomly during gamete formation, so there is an equal chance of receiving it by each gamete (means there is a 50% chance of receiving it)
• related to meiosis

Question 30

Segregation Example

Answer 30

Pair of like unit factors is present (2 factors for tall), all gametes will receive the factor for tall; Pair of unlike unit factors is present (1 factor for tall and 1 factor for dwarf), each gamete will have a 50% probability of receiving either tall or dwarf unit factor

Question 31

What do we not specify in diagrams?

Answer 31

We do not specify which one is the male and female parent.

Question 32

Square represents what?

Answer 32

An individual

Question 33

Circle represents what?

Answer 33

Gametes

Question 34

Phenotype

Answer 34

• the one that is visible and that you can see on the organism
• trait’s physical expression

Question 35

Unit Factors or Genes

Answer 35

• units of inheritance
• gametes have only one unit factor
• a genotype has two unit factors

Question 36

What was the term for genes during the time of Mendel?

Answer 36

Unit Factors

Question 37

Alleles

Answer 37

• single gene’s variants/ alternative forms

Example: Unit Factor for Tall and Dwarf, respectively

Question 38

Using Symbols to Represent Genes

Answer 38

• recessive trait’s first letter represents the character in question (example: dwarf (d))

Question 39

Recessive trait’s allele

Answer 39

in lowercase italic (Example: Dwarf, d)

Question 40

Dominant trait’s allele

Answer 40

in uppercase italic (Example: Tall, D)

Question 41

Genotype

Answer 41

• individual’s genetic make-up
• alleles written in pairs

Example: DD, Dd, dd (can have either of these examples)

Question 42

What can you identify by reading genotype?

Answer 42

The phenotype

Question 43

Homozygous/Homozygote

Answer 43

Same alleles

Example: DD, dd

Question 44

Heterozygous/Heterozygote

Answer 44

Different alleles

Example: Dd

Question 45

Punnett Square

Answer 45

• diagram that presents combining of gametes that results to genotypes and phenotypes [of the offspring]

Question 46

What can one automatically see in the Punnett square?

Answer 46

Genotypes and phenotypes [of the offspring]

Question 47

Steps for the Punnett Square

Answer 47

Step 1: Assign the gametes to columns and rows: Vertical Columns (female parent’s diagram) while Horizontal Rows (male parent’s gametes)

NOTE: ALTHOUGH THERE IS NO ISSUE IN IDENTIFYING PARENTS’ SEX, BUT IN CASE YOU WANT TO RECOGNIZE THEM, YOU NEED TO PUT THE IN THEIR POSITIONS.

Step 2: Enter the male and female genetic information into each box.

Step 3: Read the combinations in the boxes, this will give the genotypes and phenotypes of all potential offspring.

Question 48

What kind of genotype is the following gene: Dd?

Answer 48

dominant-recessive genotype

Question 49

Testcross: One Character

Answer 49

• used to determine the genotype of plants and animals
• crossing of dominant phenotype (has unknown genotype – need to find what the genotype is) with homozygous recessive individual

Question 50

What is the significance of Testcross?

Answer 50

Given the offsprings, you can now identify the genotype of the dominant one.

Question 51

Example of testcross

Answer 51

Tall Dwarf (DD) testcrossed with Dwarf plant (dd) results to All Tall (Dd); Tall plant (Dd) testcrossed with Dwarf plant (dd) results to one-half tall (Dd) and the other half is Dwarf (dd) or 1:1 tall/dwarf ratio.