Chapter 3.1. The Cell, DNA, and Mendelian Genetics

Darwin’s Posulates

1. Individuals compete to survive

2. Individuals vary in ways that affect their ability to survive

3. Some variation is heritable

Blending Inheritance

Hereditary substance of both parents mixed/blended; Elimination of Variance

Cell

Basic Unit of Life, where complex life forms are made up of billions of cells

What are cells made up of?

Genetic Material & other Structures

Prokaryotic Cells

Cells with no nucleus that make up Single Celled Organisms. (Bacteria. Blue-green Algae)

Eukaryotic Cells

• Complex cells with a nucleus that make up all organisms except Bacteria & Blue-green algae

• Common ancestor with Prokaryotic Cells.

What Are The Differences Between Prokaryotic Cells and Eukaryotic Cells?

• One has a nucleus, one does not

• One makes up single celled organisms, one makes up all organisms

• one makes up Bacteria & Blue-green Algae, one does not

What Are The Two Main Types of Cells?

1. Somatic Cells

2. Gametes

Somatic Cells

• Basic Structure

• Makes up tissues, organs, bones, & blood

Gametes

• Reproductive Cells

• Each holds Half Genetic Make-up

Gametes; Egg

• Large egg produced in human females during fetal stage of development

Gametes; Sperm (DNA with a tail)

• Small cell

• Produced continuously in adult males

Chromosomes

• Small linear bodies in a cell’s nucleus

• Replicated during cell division

• Exists in homologous pairs, in diploid organisms

• Humans: 23 Pairs

What Are The Two Types of Cell Division?

1. Mitosis

2. Meiosis

Mitosis

• Cell Division for Somatic Cells

• Creates 2 EXACT copies of chromosome pairs in each cell

• Diploid → 2 Diploids

Meiosis

• Cell Division to produce Gametes

• Creates 1 SINGLE chromosome in each cell

• Diploid → 2 Haploid Gamete

Meiosis & Fertilization

1. Haploid Sperm + Haploid Ovum Come Together (Through Meiosis)

2. New Pairs of Chromosomes Form in Diploid Zygote

3. Zygote Divides Through Mitosis, which Builds Up New Organism

What Did We Know In The 1950s?

• Cell Division

• Chromosomes contained Protein & Nucleic Acids

• DNA contains hereditary information

Francis Crick & James Watson

• Deduced the structure of DNA.