1Chromosomes and Mitosis

Chapter 1 Thompson and Thompson

1 Chromosomal Basis of Heredity• A gene is a unit

of heredity• Genes are

carried on DNA• DNA is

contained within chromosomes as chromatin

Chromosomes replicate during cell division

The chromosome complement

Chromosome analysis

Cri Du Chat results from loss of a small piece of chromosome 5

Gene Map

Chromosome pairs

Non-identical genes

Sex chromosomes

• These determine the sex of an individual– Two X chromosomes make a female

– One X and one Y a male

Two types of Cell Division

• Cells divide for two reasons– To create genetically identical

copies of themselves• This is

mitosis

– To create gametes that contain half of the chromosomes of the original cell

• This is meiosis

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The Cell Cycle

S phase

ReplicationCondensation

Schematic

DNA replication

Duplex DNA begins Replicating

Replication bubbles merge creating two duplexes

Mitosis

The stages of Mitosis

Prophase Detail

Prometaphase

Metaphase

Anaphase

Telophase

The sum total of the process

Karyotypes

Chromosome Length

Chromosome appearance