Unit 3 Lecture Notes, Lecture notes of Biology

HEREDITY

The study of heredity and variation is what?

Human chromosomes contain hundreds of genes

But what are genes? Segment, DNA, codes, traits(eye color, hair color….)

What do you know about chromosomes?

- Found in nucleus (eukaryotes)

- Occur in sets (each set from both parents)

> Pros

     - Don't need mate

     - Heredity is direct and invariable (won't change)

> Cons

     - Invariable offspring means when environment changes offspring don't survive

Sexual

     - Produced from two sex cells/parent's (gametes)

> Pros

     - Offspring not genetically identical

Cell Division

- Cell will divide during MITOSIS

 (nuclear division) and CYTOKINESIS

 (cytoplasmic division)

- What happens in cell division?

Two daughter cell are produced, they are genetically identical to each other

Ex. Starts with one parent chromosome (unreplicated), then cell division creates 2 chromosomes by

replication.

 Includes 2 sister chromatids

WHAT HAPPENS DURING THIS CELL DIVISION?

 

* Centrioles, nuclear membrane,

duplicate chromatin, nuclear envelope,

spindle fibres