Module 2 chapter 6 Flashcards
What are the 2 main stages of the cell cycle in a eukaryotic cell
- Interphase
- Mitotic (division) phase
What phase does the cell spend most of it’s time in
Interphase
Why is interphase often referred to as resting phase
As cell are not actively dividing
What makes interphase a very active part of the cycle
the cell is carrying out all it’s major functions
What are a cells major functions during interphase
- Producing enzymes or hormones
- preparing for cell division
What are the 3 main stages of interphase
- G1
- S
- G2
What is G1 phase
the first growth phase
What is G2 phase
second growth phase
What is S phase
Synthesis phase
What happens in G1 phase
organelles synthesis from proteins and replicate
Cell increases in size
What happens in S phase
DNA is replicated in the nucleus
What happens in G2 phase
- cell continues to increase in size
- energy stores are increased
- Duplicated DNA is checked for errors
Where does proteins synthesis occur is interphase
Cytoplasm
What 2 phases does the mitotic phase go through
- Mitosis
- Cytokinesis
What happens in the mitosis stage
-Nucleus divides
What happens in the cytokinesis stage
the cytoplasm divides and 2 cells are produced
What occurs in the G0 phase
the cell leaves the cycle
When the cell leaves the cycle in G0 phase is it temporary or permanently
It can be either
What are the 3 reasons for the cell leaving the cycle
- Differentiation
- DNA of a cell may be damaged
- Aging
What have a growing number of senescent cells been linked to
aged related diseases: cancer and arthritis
When a cell is differentiated why won’t it enter the cell cycle again
It becomes specialised to carry out that function indefinitely
What happens when a cell’s DNA is damaged
no longer divide and enters a period of permanent cell arrest
What are the control mechanisms of the cell cycle
Checkpoints
What do checkpoints do in the cell cycle
monitor and verify if each phase of the cycle has been accurately completed before the next stage
Where are the 3 check points
- G1 checkpoint
- G2 checkpoint
- spindle assembly checkpoint
What does the G1 checkpoint check for
- Cell size
- nutrients
- growth factors
- DNA damage
What does the G2 checkpoint check for
- cell size
- DNA replication
- DNA damage
What does the spindle assembly checkpoint check for
Chromosome attachment to spindle
What checkpoint does the cell have to pass for mitosis to proceed
Spindle assembly checkpoint
What does the term mitosis usually refer to?
the whole of cell division
What is cytoplasmic division called
cytokinesis
What happens to the cell when it divides by mitosis
It produces 2 genetically identical daughter cells
What is mitosis an important process in
- growth
- tissue repair
- asexual reproduction
What are the 4 stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
What practical would you do to study mitosis
Prepar stained squash slides of root cells
What does the term mitotic index mean?
the ratio between the number of cells undergoing mitosis and the total population of the cells
How would you calculate the mitotic index
the number of cells undergoing mitosis divided by the total number of cells
When does meiosis occur
in gamete formation
How many nuclear divisions does meiosis consist of
2
How many daughter cells are produced as a result of meiosis
4 daughter cells
What are some differences between mitosis and meiosis
Daughter cells aren’t genetically identical and have half the number of chromosomes the parent cell had
What is meiosis important for
- maintaining the chromosome number from one generation to the next
- induces genetic variation from one generation to the next
What’s the difference between chromosomes and chromatids
Chromosomes consists of 1 stand of DNA
Chromatids consists of 2 molecules of double stranded DNA
What’s the structure of a chromatid
thin and long fibrus structure
What’s the structure of a chromosome like
thin and ribbon like structure
What is a diploid
A cell or organism that has paired chromosomes one from each parent
What is an example of a dipoid
Human egg and sperm cell
What is a haploid
When a cell has half the number of chromosomes
What division type would a haploid cell go through
Meiosis
What is crossing over in meiosis
2 chromosomes of homologous pair exhange equal segments with each other
When does crossing over occur
First divion of mieosis
What has the chromosome done at the first division of meiosis
Replicated into 2 strands called sister chromatids
How does crossing over cause genetic variation
creates new combinations of genes in the gametes that are not found in either parent , thus genetic diversity
What happens to cells that leave the cell cycle
they become specialised and develop specific cellular structures
In multicellular organisms do cells work together or alone
rarely work alone and are organised into groups
Where are similar cells grouped together
In tissues and different tissues are organised into organs
What do various organs work together to make
Organ systems, many organ systems make up the organism
What is a specialised feature of a red blood cell
- Contain haemoglobin
- No nucleus
- bi-concave
What are the specilised features of a root hair cell
- Large surface area
- lots of mitocondria
