Presentations tomorrow

1. Dress nicely tomorrow2. Recommended to practice your

comments/ppt tonight with your parents/siblings to see what makes sense, how long it takes, etc.

3. Each person will have literally 5 minutes. 4. You have until Wednesday night 11:59pm to

email me the ppt.

Schedule / switching off rooms. • 1:30 – 1:35: Seth - Rm. 243 • 1:35-1:40: Netanel - Rm. 244• 1:40 – 1:45: Joey S – Rm. 243• 1:45 – 1:50: Yosef C - Rm. 244• 1:50 – 1:55: Aryeh - Rm. 243• 1:55 – 2:00: David - Rm. 244• 2:00 – 2:05: Gilad - Rm. 243• 2:05 – 2:10: Jeremy - Rm. 244• 2:10 – 2:15: Jonah - Rm. 243• 2:15 – 2:20: Ben - Rm. 244• 2:20 – 2:25: Max - Rm. 243• 2:25 – 2:30: Joey - Rm. 244• 2:30 – 2:35: Jordan - Rm. 243• 2:35 – 2:40: Asael - Rm. 244

Dihybrid cross work problems

• Review problems

Complications with Mendelian Genetics

1. Incomplete dominance2. Codominance3. Multiple alleles4. Multiple-gene determination

Incomplete dominance

• Incomplete dominance: This is when there are two different alleles but a heterozygous individual expresses something in the middle between the two homozygous alternatives.

Example:

Codominance

• Codominance is when there are two alleles but the heterozygous individual expresses BOTH of the homozygous alternatives.

Heterozygous plant expresses BOTH red and white- not something in the middle.

Multiple alleles

• There are some cases in which there are not just two options for what the gene can be.

• Example: Imagine a flower that had options of B (blue), R (red), G (green) and W (white).

• There are all sorts of possibilities. Some of the alleles might be normal dominance. Others might be incomplete or codominance.

Multiple-Gene Determination

• Single-gene determination is when a single location on a single chromosome decides what the phenotype is.

• Multiple-gene inheritance is when a phenotype is determined by the net total of many different genes on many different chromosomes.

• Imagine height- there might a single gene that determines how long a single bone is. Then your height is made up of many bones, muscles, etc.

Matching

• Multiple alleles

• Multiple-gene determination

• Many different genes contribute to the phenotype

• For a single gene there are more options than just 2 alleles.