Genetics and Heredity

Genetics and Heredity

Learning Targets

●Students will be able to define and differentiate between the terms gene, allele, and trait.

●Students will be able to explain the difference between dominant and recessive traits and how they are passed down.

●Students will be able to predict the probability of inheriting certain traits using Punnett squares.

Reorder

Reorder the following from largest to smallest

• Cell

• Nucleus

• Chromosome

• DNA

• Gene

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Nucleus

Most cells have a nucleus. The nucleus is like a library that stores information (DNA)

Inside the nucleus

The nucleus stores chromosomes

Chromosomes are X-shaped structures
made up of organized DNA.

Humans have 23 pairs of chromosomes or 46 total.

Multiple Choice

What does the nucleus store?

• Waste

• Water

• DNA

• Cells

Multiple Choice

What are chromosomes?

• X-shaped structures made of organized DNA

• A collection of waste stored within the cell

• Round tubes that transport water

• B-shaped structures made of unorganized DNA

DNA and Genes

Our DNA is full of very long strands.

Parts of each strand can be read as individual "code" or "instructions"

These "codes" are genes. We have millions of genes that make us up.

Every trait, every detail about us is decided and directed by one or more genes.

Genes are pieces of DNA that code for a trait like eye color.

Multiple Choice

What are genes?

• Organelles that produce ATP

• A type of pants

• Pieces of DNA that don't code for anything

• Pieces of DNA that code for a trait

Genotype vs. Phenotype

The physical features we can observe:

Ex: hair color, eye color, nose shape

Phenotype

ALL of our genetic information

Ex: DNA and Genes

Genotype

Match

Match the following

• Genotype Definition

• Phenotype Definition

Genotype Picture

Phenotype Picture

ALL of our genetic information

The physical features we can observe

• Genotype Picture

• Phenotype Picture

• ALL of our genetic information

• The physical features we can observe

Alleles

Alleles are different versions or variations of one gene. There are always two copies, one inherited from from mom and one from dad.

 

Some alleles are stronger and show up in the phenotype, called dominant traits they are written using capital letters

 

Some alleles are weaker and will not show up in the phenotype, called recessive traits they are written using lowercase letters

Dominant or Recessive?

Dominant alleles are always expressed, even when there is just one copy. These alleles are written as a capital letter.

Example: B

Recessive alleles are only expressed when there are 2 copies. These alleles are written as a lowercase letter.

Example: b

Fill in the Blank

Recessive alleles are only expressed when there are ___ copies. These alleles are written as a lowercase letter.

Multiple Choice

A recessive allele is represented by

• A capital letter

• A lowercase letter

Multiple Choice

A dominant allele is represented by

• A capital letter

• A lowercase letter