Cell Division Flashcards
What are the 2 main stages of the cell cycle?
interphase
mitotic
What happens during interphase?
5 things
DNA replicated + checked for errors Protein synthesis in the cytoplasm Mitochondria grow + divide Chloroplasts grow + divide metabolic processes
There are 3 stages of interphase, what are they called?
G1
S
G2
What happens in the G1 stage of interphase?
Proteins are synthesised
organelles replicate
cell increases in size
What happens in the S phase of interphase?
DNA is replicated in the nucleus
What happens in the G2 stage of interphase?
cell increases in size
the replicated DNA is checked for errors
What 2 stags are involved in the mitotic phases of the cell cycle?
mitosis
cytokinesis
What happens in the G0 stage of the mitotic phase?
the cell leaves the cycle permanently/temporarily
What are the reasons for going into the G0 stage?
differentiation- cell becomes specialised so can no longer divide
DNA may be damaged
Growing numbers of senescent cells
G1 checkpoint is at the end of the G1 stage before the S phase, what is the purpose of this checkpoint?
if the cell satisfies requirements it triggers DNA replication
G2 checkpoint is at the end of the G2 stage before the Mitotic phase, what is the purpose of this checkpoint?
checked for DNA without errors, if satisfies the requirements it initiates the being of mitosis
Describe the cells that mitosis create?
2 daughter cells produced by a parent cell would be genetically identical, each will have the exact same copy of DNA
What are 2 identical DNA molecules called?
chromatids
What is the region called where the 2 chromatids joined together?
centromere
What is the order of Mitosis?
prophase
metaphase
anaphase
telophase
What happens in prophase?
chromatic fibre coil and condense, which form
chromosomes
the nucleus disappears
the nuclear membrane breaks down
spindle fibres link the 2 poles of the cell
spindle fibres attach to specific areas on the centromere
nuclear envelope disappears
What happens in Metaphase?
chromosomes are moved by the spindle fibres to form the metaphase plate
What happens in anaphase?
the centromeres holding the pairs of chromatids divide
The chromatids are separated and pulled to the opposite poles of the cell by the shortening of the spindle fibres.
What happens in Telophase?
2 new chromosomes assemble and the nuclear envelope reforms
chromosome uncoil and the the nucleolus is formed
cytokinesis begins
During cytokinesis in animals cells a cleavage furrow is formed around the middle, what causes this?
the cell surface membrane of the animal cell gets pulled in by the cytoskeleton
Why can’t plant cells form cleavage furrows?
because they have cell walls
What are the 2 sex cells called?
Gametes
What is a fertilised egg called?
zygote
Diploid
2 chromosomes inherited form each parent
haploid
daughter cells that contain 1/2 the chromosomes number of the parent
How many daughter cells are produced in meiosis ?
4
What is a Homologous chromosome?
matching sets of chromosomes
diploid
define Alleles
different variations of the same genes
What happens in Meiosis 1 prophase 1?
chromosomes condense
nuclear envelope disintegrates
nucleolus disappears
spindle fibres formation begins
Homologous chromosomes pair up and form bivalents
What happens in meiosis 1 metaphase 1?
same as mitosis 1 but the pairs of homologous chromosomes line up at the metaphase plate
The orientation is random
random assortment, resulting in different combination of alleles
What happens in meiosis 1 anaphase 1?
Homologous chromosomes are pulled to opposite poles, the chromatids stay together
Crossing cover occurs
chiasmata - chromatids break and rejoin = recombinant chromatids
What happens in meiosis 1 telophase 1?
chromosome assemble at each pole
nuclear membrane reforms
chromosomes un coil
undergoes cytokinesis
Diploid —–> haploid
What shape are erythrocytes?
And why?
biconcave
increased SA:V
more space for haemoglobin
don’t have a nucleus so more space for haemoglobin
What are the adaptations of neutrophils?
multi lobed nucleus - easier to fit into small gaps
granular cytoplasm - contains lysosomes to attack pathogens
What are the adaptations of sperm cells?
Flagellum- enable movement
Many mitochondria to supply energy
The acrosome on the head of the sperm contains enzymes
What are the Adaptations of palisade cells?
contain chloroplasts to absorb light
rectangle shape to form a continuose layer
Thin cell walls - shorter diffusion distances
large vacuole to maintain turgor pressure
What are the adaptations of root hair cells?
long extensions that increase SA:V —-> maximises the uptake of water+ minerlas
What are the adaptations of guard cells?
small openings = stomata
sides are asymmetrical to open and close stomata
Adaptations of squamous epithelium
made of flat cells, only 1 cells thick
present where rapid diffusion is needed
Adaptations of ciliated epithelaim
have Cilla on the surface on 1 side
beat rhythmically—–> mucus can be swapped away
goblet cells are present
Adaptations of cartilage
connective tissue
contains elastin
contains collegen
made from chondrocyte cells
Adaptations of muscle tissue
contain myofibrils
able to shorten and contact
Adaptations of epidermis
single layer of closely packed cells covered by a cuticle
have stomata
Adaptations of xylem tissue
vascular tissue transport of water and minerals
elongated hollow dead cells
lignified
Adaptations of phloem tissue
transport of nutrients
collum of sieve tubes
have bordered pits
What are undifferentiated cells called?
stem cells
What are the 3 types of stem cell potency
totipotent
pluripotent
multipotent
define totipotent
can differentiate into any type of cell
define pluripotent
can form all tissue types but not whole organisms
define multipotent
stem cells that can only form a range of cells within a curating type of tissue
Where can you find plant stem cells?
meristematic tissue
vascular cambium
Where can you find Animal stem cells?
embryonic stem cells = early stages of embryo developemt
umbilical chords
bone marrow
What happens in meiosis 2 prophase 2?
chromosomes condense
nucleus envelope breaks doen
spindle fibre formation begins
What happens in meiosis 2 metaphase 2?
Individual chromosomes assemble on the metaphase plate.
What happens in meiosis 2 anaphase 2?
chromatids of individual chromosomes are pulled to opposite poles
division of the contromeres
What happens in meiosis 2 telophase 2?
Chromatids assemble chromosomes uncoil forming chromatin nuclear envelope becomes visible nuclear envelope reforms Cytokinesis results in 4 daughter cells genetically different .
