5.4 Inheritance

• Biologie
• 9th Grade

5.4 Inheritance

TB Page 132

What is Inheritance?

Inheritance is the process by which genetic information is passed on from parent to child. This is why members of the same family tend to have similar characteristics.

Homologous (matching) pairs

Homologous pair of chromosomes

Homologous pair of chromosomes

Workbook Page 143

Questions 16 till 19

DOMINANT

recessive

Yolanthe & 

Wesley

Other couple

Workbook Page 143

Question 20

Darwin                                                               Mendel

Terms in genetic crosses

• P = Parental = the parents
• F1 = first new generation of offspring = the children
• F2 = 2nd generation = the grandchildren

02:28

Look at Table 5.2 on page 134.
Which flower colour is dominant?

02:38

Again: Table 5.2 on page 134.
Which stem length is recessive?

03:51

What does 'F1 generation' mean?

Homozygous, Heterozygous

An organism has two identical alleles of a gene:

Homozygous : AA  or  aa         /        RR  or  rr    etc. (Homo = 'same')

• homozygous dominant: AA   
• homozygous recessive: aa
  
  

An organism has two different alleles of a gene:

Heterozygous: Aa                  /           Rr         etc. (Hetero = 'different')

Phenotypes versus genotypes!

Phenotype: purple 

Genotype?

Phenotypes versus genotypes!

Phenotype: white

Genotype?

Genetic crosses: white x white

x

F 1

Genetic crosses: purple x purple

x

F 1

Genetic crosses: purple x purple

x

F 1

Workbook Page 144

Questions 21 and 22

Two types of crosses

Homozygous : AA x aa         /        RR x rr  etc. (Homo = 'same')

Heterozygous: Aa x Aa       /        Rr x Rr  etc. (Hetero = 'different')

Two types of crosses

Homozygous : AA x aa         /        RR x rr  etc. (Homo = 'same')

Gametes: A and A  ,  a and a    /    R and R  ,  r and r

Heterozygous: Aa x Aa       /        Rr x Rr  etc. (Hetero = 'different')

Gametes: A and a , A and a    /      R and r , R and r

TB page 136

Steps for succesfully solving genetics problems

04:41

The F1 consists of all purple flowers even though 1 parent is white. Why?

05:08

What is the term for a characteristic that is present but not (yet) expressed?

1. dominant
2. recessive

Ss: Homozygous or heterozygous for the Spot allele?

1. Homozygous
2. Heterozygous

Cat without Spots?

1. SS
2. Ss
3. ss

Spotty cat coud be Ss and...

1. SS
2. Ss
3. ss

Answers:

Today:

• Quick quiz
• Homework check
• Practice

An exampe of a heterozygous genotype is...

1. BB
2. Bb
3. bb

When you cross BB x bb, the offspring will be

1. 100% BB
2. 100% Bb
3. 50% Bb and 50% bb
4. 25% BB, 50% Bb, 25% bb

When you cross Bb x bb, the offspring will be

1. 100% BB
2. 100% Bb
3. 50% Bb and 50% bb
4. 25% BB, 50% Bb, 25% bb

When you cross Bb x Bb, the offspring will be

1. 100% BB
2. 100% Bb
3. 50% Bb and 50% bb
4. 25% BB, 50% Bb, 25% bb

Answers:

Textbook page 150

1. Question 27 - together
2. then...
3. Practice question - by yourself