CELLS AND HEREDITY

Introduction

November 30, 2010• New Vocabulary List – back of spiral

– Title of new list – “Heredity”

– DNA -- a molecule found in cells that contains all the instructions for making new cells.

– CHROMOSOME --found inside the nucleus of a cell, this structure contains the DNA

– MITOSIS --occurs in eukaryotic cells, and is a process of cell division that forms two new nuclei, each of which has the same number of chromosomes.

Vocabulary

• Heredity -- The passing of traits from parents to offspring

• Genetics -- the study of how traits are passes on, or inherited.

Vocabulary (Heredity List)• Prophase – the first phase of mitosis, when the

nuclear membrane disappears.• Metaphase – the second phase of mitosis, when

replicated chromosomes line up in the middle of the cell.

• Anaphase – the third phase of mitosis, when the chromatids are pulled to opposite sides of the cell by spindle fibers

• Telophase – the fourth phase of mitosis, when the nuclear membranes reform, and the cell membrane starts to pinch in to divide the cells.

Vocabulary•Interphase – Before mitosis begins,

chromosomes are copied.•Cytokinesis – after mitosis ends -- the

division of cytoplasm of a cell.•Chromatid - a pair of identical DNA

molecules after DNA replication, joined at the centromere.

•Centriole – paired cylindrical organelles, arranged at right angles to each other, located at the center of the spindle fibers.

Single Cell and Multi-Cell Reproduction

Prokaryotes

• Single-celled organisms– Bacteria– archaea

• Defined as having no nucleus or membrane around the organelles

• Most have cell walls • Contain a single circular

chromosome in the nucleoid region

• Divide through binary fission– Cell splits into two parts– Each cell has a copy of the DNA

• formed about 3.5 billion years ago

Eukaryotes

• The cells of protozoa, higher plants and animals

• highly structured -- complex

• Tend to be larger than the cells of bacteria

• Cell division is in three stages– Interphase– Mitosis– cytokinesis

See Animation

The Cell Cycle

• This is how a eukaryotic cell divides and replicates

• Cells appear to be dividing at times, and then resting between divisions

• Interphase is when a cell appears to be resting—but many important activities take place at this time.

See Animation See Video

Mitosis http://www.cellsalive.com/mitosis.htm

Mitosis