20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
Biology Exam revision:
Cell Division and Inheritance
Why cells divide?
Cells divide to
• Grow (baby to adult)
• Repair (replace damage cells)
• Reproduce (especially in single celled organisms)
There are two types of main types of cell division.
1. Mitosis (makes body Somatic cells.)
2. Meiosis has sex cells (gametes sperm and egg)
MITOSIS:
Mitosis is an organised division of the nucleus of the cell. There are four stages in
mitosis. (Prophase, metaphase, Anaphase and telophase) (PMAT).
• No genetic variation cells are clones.
• Think for it as ‘copy and paste’ for cells.
• Ech new cell have the same number of chromosomes as parent (so if human has
46 chromosomes as the parent daughter cells also have 46 chromosomes.
• Purpose to make new cells that are the same as the old once. This helps you
grow and heal.
• Process; one cell splits into two identical cells in four steps. (Prophase,
metaphase, Anaphase and telophase) (PMAT).
THE NUCLEAS IS STILL THERE AND ITS GOING TO GO
AWAY LATTER ON BUT THIS IS A STAGE.WHERE ITS
ACTUALLY STILL THEIR CHROMOSOMES ARE VISIBLE IN
FACT WE CAN SAY CONDESING.WHICH MEANS THEY ARE
THICKNING AND VISIBLE. (from video)
In prophase, chromatin continues to wind into a
condensed from of DNA called a bivalent chromosome.
Each chromosome has a distinctive ‘H’ shape in which two
parallel ‘sister’ Chromatids are joined at the centromere.
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
,20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
while the DNA molecule is condensing into a
chromosome the nuclear membrane breaks
down, and a number of protein threads
spread from one end of the cell to the other.
These protein threads link together at each
cell pole to form a spindle. (from book)
cell gets ready to split. DNA packs up nucleus
goes away and structure forms to pull apart DNA.
METAPHASE: M for middle
because in this stage the chromosomes line up in the middle
of the cell. The nucleus has been disassembled it’s no longer
there, so we have got the chromosomes in the middle waiting
there. From video
during metaphase the newly formed chromosome migrate to the canter (equator of the cell, the
spindle then attaches to the centromere of each chromosome. At this point checkpoint M
checks that the spindle fibre is correctly attached to each centromere before the cell
progresses to the next stage. (from book).
In metaphase chromosomes line up in the middle of the cell before being separated. (From Ai )
ANAPHASE: Away
The chromosomes move away they move to the
opposite sides of the cell, so they are moving towards to the poles of the
cells know one thing to point out this chromosome they are not moving by
themselves they have something called spindles are fibres that help move
the chromosomes to the end kind of helps them move along. (centriole
also help) (from video)
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
,20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
During Anaphase the sister chromatids of each bivalent chromosomes
separate at the centromere. This breaks apart the distinctive ‘H’ shape into
two individuals (identical) DNA molecules, and each chromatid becomes a
single independent chromosome the spindle fibres pull each identical
chromosomes to opposite poles of the cell this occurs for each of the 46
chromosomes in a human cell. The results is 46 individual chromosomes
at each pole of the cell. (from book)
Anaphase is when the chromosomes that were lined up in the middle get
pulled apart to opposite sides of the cell with help of spindles and
centriole. (from Ai)
TELOPHASE: T FOR TWO
in telophase the chromosomes are actually at
complete opposite ends and new nuclei are
forming on each side to make two new cells the
nuclei are starting to surround the chromosomes
to both sides I like to think the T is for two you can
really see this steps that the end goal is going to
be two cells and in the human body they are each
going to have 46 chromosomes and again
remember they are identical. (from book)
Telophase is a final stage of cell division where two new nuclei from around
the separated chromosomes its like creating two new rooms for one. (From
Ai)
CYTOKINESIS:
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
, 20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
cytokinesis is responsible for the final
separation into two cells by splitting the cytoplasm which completes after
the PMAT mitosis stages.
Describe each stage of mitosis. Prophase: Chromosomes
condense and the nuclear
envelope breaks down.
Metaphase chromosomes line up
in the middle of the cell.
Anaphase sister chromatids
separate and move to opposite
poles.
Telophase; Chromosomes
decondense and nuclear envelopes
form.
Cytokinesis: the cell divides into
two daughter cells.
Explain the difference the S phase S Phase. DNA replication occurs
and G2 phase in interphase G2 phase: the cell prepares for
mitosis and organelles duplication.
Describe the three different G1 checkpoint. Checks for DNA
checkpoints that ensure that the damage and cell size.
cell cycle progresses correctly. G2 checkpoint: checks for DNA
replication completion and DNA
damage.
M checkpoint. Checks for
chromosomes attachment to the
spindle.
Identify the phase of mitosis shown Metaphase because chromosomes
in figure. are lined up in the middle.
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
Biology Exam revision:
Cell Division and Inheritance
Why cells divide?
Cells divide to
• Grow (baby to adult)
• Repair (replace damage cells)
• Reproduce (especially in single celled organisms)
There are two types of main types of cell division.
1. Mitosis (makes body Somatic cells.)
2. Meiosis has sex cells (gametes sperm and egg)
MITOSIS:
Mitosis is an organised division of the nucleus of the cell. There are four stages in
mitosis. (Prophase, metaphase, Anaphase and telophase) (PMAT).
• No genetic variation cells are clones.
• Think for it as ‘copy and paste’ for cells.
• Ech new cell have the same number of chromosomes as parent (so if human has
46 chromosomes as the parent daughter cells also have 46 chromosomes.
• Purpose to make new cells that are the same as the old once. This helps you
grow and heal.
• Process; one cell splits into two identical cells in four steps. (Prophase,
metaphase, Anaphase and telophase) (PMAT).
THE NUCLEAS IS STILL THERE AND ITS GOING TO GO
AWAY LATTER ON BUT THIS IS A STAGE.WHERE ITS
ACTUALLY STILL THEIR CHROMOSOMES ARE VISIBLE IN
FACT WE CAN SAY CONDESING.WHICH MEANS THEY ARE
THICKNING AND VISIBLE. (from video)
In prophase, chromatin continues to wind into a
condensed from of DNA called a bivalent chromosome.
Each chromosome has a distinctive ‘H’ shape in which two
parallel ‘sister’ Chromatids are joined at the centromere.
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
,20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
while the DNA molecule is condensing into a
chromosome the nuclear membrane breaks
down, and a number of protein threads
spread from one end of the cell to the other.
These protein threads link together at each
cell pole to form a spindle. (from book)
cell gets ready to split. DNA packs up nucleus
goes away and structure forms to pull apart DNA.
METAPHASE: M for middle
because in this stage the chromosomes line up in the middle
of the cell. The nucleus has been disassembled it’s no longer
there, so we have got the chromosomes in the middle waiting
there. From video
during metaphase the newly formed chromosome migrate to the canter (equator of the cell, the
spindle then attaches to the centromere of each chromosome. At this point checkpoint M
checks that the spindle fibre is correctly attached to each centromere before the cell
progresses to the next stage. (from book).
In metaphase chromosomes line up in the middle of the cell before being separated. (From Ai )
ANAPHASE: Away
The chromosomes move away they move to the
opposite sides of the cell, so they are moving towards to the poles of the
cells know one thing to point out this chromosome they are not moving by
themselves they have something called spindles are fibres that help move
the chromosomes to the end kind of helps them move along. (centriole
also help) (from video)
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
,20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
During Anaphase the sister chromatids of each bivalent chromosomes
separate at the centromere. This breaks apart the distinctive ‘H’ shape into
two individuals (identical) DNA molecules, and each chromatid becomes a
single independent chromosome the spindle fibres pull each identical
chromosomes to opposite poles of the cell this occurs for each of the 46
chromosomes in a human cell. The results is 46 individual chromosomes
at each pole of the cell. (from book)
Anaphase is when the chromosomes that were lined up in the middle get
pulled apart to opposite sides of the cell with help of spindles and
centriole. (from Ai)
TELOPHASE: T FOR TWO
in telophase the chromosomes are actually at
complete opposite ends and new nuclei are
forming on each side to make two new cells the
nuclei are starting to surround the chromosomes
to both sides I like to think the T is for two you can
really see this steps that the end goal is going to
be two cells and in the human body they are each
going to have 46 chromosomes and again
remember they are identical. (from book)
Telophase is a final stage of cell division where two new nuclei from around
the separated chromosomes its like creating two new rooms for one. (From
Ai)
CYTOKINESIS:
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
, 20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
cytokinesis is responsible for the final
separation into two cells by splitting the cytoplasm which completes after
the PMAT mitosis stages.
Describe each stage of mitosis. Prophase: Chromosomes
condense and the nuclear
envelope breaks down.
Metaphase chromosomes line up
in the middle of the cell.
Anaphase sister chromatids
separate and move to opposite
poles.
Telophase; Chromosomes
decondense and nuclear envelopes
form.
Cytokinesis: the cell divides into
two daughter cells.
Explain the difference the S phase S Phase. DNA replication occurs
and G2 phase in interphase G2 phase: the cell prepares for
mitosis and organelles duplication.
Describe the three different G1 checkpoint. Checks for DNA
checkpoints that ensure that the damage and cell size.
cell cycle progresses correctly. G2 checkpoint: checks for DNA
replication completion and DNA
damage.
M checkpoint. Checks for
chromosomes attachment to the
spindle.
Identify the phase of mitosis shown Metaphase because chromosomes
in figure. are lined up in the middle.
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
20251202223012_692f68740f839_biology_exam_revision.docx
