Heredity and Evolution Review

Traits are passed from parents to offspring through genes in DNA.

DNA is a type of molecule that carries the inherited information passed from parents to offspring.

A gene is a segment of DNA that contains the instructions for building a product, usually a protein.

A chromosome is a cell structure that contains an organism’s DNA. Each chromosome is made up of one long molecule of DNA that includes many genes along its length.

Inside a cell, there is an enclosed structure called the nucleus. The nucleus contains the cell’s chromosomes.

Purpose: Growth and Repair.


1 division



2 cells

46 chromosomes in each cell.

Purpose: Create gametes

2 divisions



4 cells
23 chromosomes in each cell.

​Meiosis

two different alleles
Ex: Aa

heterozygous

Same alleles

Ex: AA or aa

AA= homozygous dominant
aa= homozygous recessive

Homozygous

Symbols

• Circle = female
• Square = male
• Normal or without

trait = unshaded

• Trait = shaded

Generations

• Each generation

is (often) labeled
with a Roman
numeral.

• Oldest generation

at top of pedigree

• Current

generation at
bottom

is the gradulal change in organisms over time

Fossils of ancient organisms have similar structures and DNA than that of organisms today, suggestiing they are ancestors of living organisms.

Nature selects those with desirable traits, and those survive and reproduce. Over time, the desirable trait becomes the most common because it has been past down generation after generation.