V4 Inheritance 6

Welcome!
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  • Have the dihybrid cross worksheet open on your computer
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Slide 1: Slide
BiologieMiddelbare schoolvwoLeerjaar 4

This lesson contains 20 slides, with interactive quizzes and text slides.

Items in this lesson

Welcome!
Have the following ready:

  • Have joined the lessonup
  • Have the dihybrid cross worksheet open on your computer

Slide 1 - Slide

Roadmap for today:
First half, with the whole group:
  • discuss dihybrid cross worksheet
  • introduction to non-Mendelian inheritance (take notes!)
*break*
Second half, individually or in small groups:
  • practice with sex-linked inheritance (worksheet)
  • practice with codominance 

Slide 2 - Slide

What is/are correct ways to write the genotype for heterozygous brown-eyed, curly-haired?
A
AaBb
B
BbcC
C
BrCs
D
BbCc

Slide 3 - Quiz

What are the possible gametes for someone with the genotype AaBB?
A
Aa, BB, AB, and aB
B
AB and aB
C
AaBB, AABB, and aaBB

Slide 4 - Quiz

Dihybrid cross worksheet Q1: What is the chance of producing offspring with phenotype Tall/Green?
A
25%
B
50%
C
75%
D
100%

Slide 5 - Quiz

Dihybrid cross worksheet Q2: What is the phenotypic ratio of the offspring?

Slide 6 - Open question

Dihybrid cross worksheet Q3: What are the genotypes of the parent dogs?
A
DdRr and DdRr
B
DDRr and DdRR
C
DDRR and DDRR
D
DDRr and DdRr

Slide 7 - Quiz

Dihybrid cross worksheet Q3: How do you know that the genotypes of the parent dogs are both DdRr?

Slide 8 - Open question

Dihybrid cross worksheet Q3: What is the phenotypic ratio of the offspring?
A
3:1:0:0
B
9:3:3:1
C
1:1:1:1
D
9:2:2:2

Slide 9 - Quiz

Non-mendelian inheritance
Mendel’s model of inheritance assumes that:
  • Each trait is controlled by a single gene
  • Each gene has only 2 alleles
  • There is a clear dominant-recessive relationship between the alleles

Most genes do not meet these criteria.

Slide 10 - Slide

Can you think of an example of non-Mendelian inheritance?

Slide 11 - Mind map

Slide 12 - Slide

Polygenic inheritance
Polygenic inheritance occurs when multiple genes are involved in controlling the phenotype of a trait. The phenotype is an accumulation of contributions by multiple genes. These traits show continuous variation and are referred to as quantitative traits. 
For example: human height

Slide 13 - Slide

Continuous variation
When multiple genes act together to produce a physical (phenotypic) character, a gradation or range of differences occur.

Slide 14 - Slide

Pleiotropy
Pleiotropy refers to an allele that has more than one effect on the phenotype. 
Examples: diseases such as sickle cell anemia and cystic fibrosis. In these diseases, multiple symptoms can be traced back to one defective allele.

Slide 15 - Slide

Incomplete dominance
Situation where 2 alleles 'blend' to form a hybrid ("inbetween") phenotype.

Slide 16 - Slide

Co-dominance
In codominance, both traits appear. 
Co = together

Slide 17 - Slide

Sex-linked inheritance
Gene is located on the X or Y chromosome.

In practice almost always on the X.

Slide 18 - Slide

Inheritance: what have we done so far and what is still to come?
Done:
  • Vocabulary: genes, alleles, homozygous, heterozygous, dominant, recessive, carrier...
  • Incomplete dominance
  • Monohybrid crosses
  • Dihybrid crosses
Started:
  • Sex-linked inheritance
  • Co-dominance
Still to come
  • Multiple alleles
  • Lethal alleles
  • (Epigenetics)

Slide 19 - Slide

Self-directed work time:
Mandatory:
  • Worksheet sex-linked inheritance
  • Exercises Codominance
Optional: 
  • Check answers dihybrid cross worksheet
  • extra exercises dihybrid cross
  • choose an article about genetics to read (see Classroom or ScienceNews.org)
  • help your classmates
  • study
You may work together (put everyone's names in the worksheet title)

Slide 20 - Slide