Year 1
Biology Department
Cell Cycle and the Immune Response
Name:
Teacher:
1
, Cell division
The cell cycle in eukaryotes
In multicellular organisms, not all cells keep their ability to divide. The ones that do follow a process
called the cell cycle.
The cell cycle starts consists of a period of growth and DNA replication, called interphase and a
period of cell division, called mitosis. Interphase is the longest phase in the cycle, normally longer
than the whole of mitosis, unless the cell is rapidly dividing. It is split into three separate growth
stages. These are called G1, S and G2.
G1
The cell grows.
Increase in the number
of organelles
Proteins are made. S= Synthesis of
ATP synthesised the DNA
(replication)
Synthesis
phase
G2
Mitosis -the stages:
The cell keeps growing.
• Prophase
Proteins are made.
• Metaphase ATP synthesised
• Anaphase
• Telophase
2
, Homologous chromosomes are chromosomes that are the same size, the same shape and the
centromere is in the same place. They contain the same genes. One is maternal – from mum and
one paternal- from dad.
All somatic (non sex) cells in the body contain 46 chromosomes in 23 homologous
pairs. Therefore when a new (daughter) cell is produced it will also contain 46
chromosomes.
MATHS Question
A scientist observes a section of growing tissue under the microscope. He counts 100 cells
undergoing mitosis. Of those, 10 cells are in metaphase. One complete cell cycle lasts 15 hours.
How long do the cells spend in metaphase? Give your answer in minutes
Interphase
During interphase the following occurs:
• DNA replicates,
• ATP synthesised,
• Organelles synthesised including centrioles,
• Proteins synthesised
DNA Replication in Interphase:
• Chromosomal DNA is replicated exactly and the two pieces of DNA are held together by the
centromere.
• If the copies are not done accurately mutations may occur and daughter cells will not
receive identical genetic material.
• Following mitosis the two new cells will contain one of each sister chromatids.
centromere
3
Biology Department
Cell Cycle and the Immune Response
Name:
Teacher:
1
, Cell division
The cell cycle in eukaryotes
In multicellular organisms, not all cells keep their ability to divide. The ones that do follow a process
called the cell cycle.
The cell cycle starts consists of a period of growth and DNA replication, called interphase and a
period of cell division, called mitosis. Interphase is the longest phase in the cycle, normally longer
than the whole of mitosis, unless the cell is rapidly dividing. It is split into three separate growth
stages. These are called G1, S and G2.
G1
The cell grows.
Increase in the number
of organelles
Proteins are made. S= Synthesis of
ATP synthesised the DNA
(replication)
Synthesis
phase
G2
Mitosis -the stages:
The cell keeps growing.
• Prophase
Proteins are made.
• Metaphase ATP synthesised
• Anaphase
• Telophase
2
, Homologous chromosomes are chromosomes that are the same size, the same shape and the
centromere is in the same place. They contain the same genes. One is maternal – from mum and
one paternal- from dad.
All somatic (non sex) cells in the body contain 46 chromosomes in 23 homologous
pairs. Therefore when a new (daughter) cell is produced it will also contain 46
chromosomes.
MATHS Question
A scientist observes a section of growing tissue under the microscope. He counts 100 cells
undergoing mitosis. Of those, 10 cells are in metaphase. One complete cell cycle lasts 15 hours.
How long do the cells spend in metaphase? Give your answer in minutes
Interphase
During interphase the following occurs:
• DNA replicates,
• ATP synthesised,
• Organelles synthesised including centrioles,
• Proteins synthesised
DNA Replication in Interphase:
• Chromosomal DNA is replicated exactly and the two pieces of DNA are held together by the
centromere.
• If the copies are not done accurately mutations may occur and daughter cells will not
receive identical genetic material.
• Following mitosis the two new cells will contain one of each sister chromatids.
centromere
3
