2.2: All Cells Arise From Other Cells

Why do we need to make new cells?

Asexual reproduction, growth, repair of tissue, replacement of cells

What is the word for the complete set of chromosomes in an organism?

Karyotype

Label the diagram

a and d: Pair of homologous chromosomes

b: Centromere

c: DNA replication

e and f: Sister chromatids

What are chromosomes made of?

A chromosome is made of a material called chromatin which is a mixture of DNA and the protein histone

Define a homologous pair

A pair of chromosomes whcib have exactly the same genes but different alleles

Label the diagram

a: Chromosomes

b: Chromatin

c: Histone proteins

d: DNA

If a diploid cell has 46 chromosomes and a haploid cell has 23, what does that mean? Give an example for each

A diploid cell is a somatic cell (body cell), an example of this would be a muscle cell. A haploid cell is a gamete, an example of this would be a sperm cell.

What are the stages of mitosis (in order)?

Interphase, prophase, metaphase, anaphase, telophase (and cytokenesis but isn;t technically part of mitosis)

What happens in interphase?

The cell grows in size

The number of organelles increases

The cell is carrying out normal functions

DNA is replicated (each chromosome now consists of two sister chromatids)

What happens in prophase?

Spindle forms

The nuclear envelope breaks down

Chromosomes condense and become visible

Centrioles move to poles of the cell

What happens in metaphase?

Spindle fibres attach to centromeres

Spindle fibres change length to arrange chromosomes around equator of the cell

What happens in anaphase?

Centromerews divide in two

Spindle fibres pull sister chromatids apart (and to poles of cell)

What happens in telophase?

Chromosomes are at the poles of cells

Chromosomes condense into chromatin

Nuclear envelope and nucleus reform

What happens in cytokenesis?

Plasma membrane and cytoplasm divide in two to form two genetically identical daughter cells

Give a stage of the cell cycle to each of these labels

a: Anaphase

b: Prophase

c: Prophase

d: Telophase