Topic 3 - cell division Flashcards
Nucleus function
Contains chromosomes made of DNA + contain genes that control the synthesis of proteins
Mitochondria function
Site of aerobic respiration to produce energy
Lysosome defi.
- Breakdown of unwanted structures
- destruction of whole cells to be replaced
RER defi.
- rough endoplasmic reticulum
- ribosomes attached to surface
- proteins made on ribosomes are transported through here to other parts of cell
SER defi.
- smooth endoplasmic reticulum
- makes lipids + steroids
Golgi apparatus defi.
Modifies proteins and packages them into vesicles for transport
Centriole defi.
- Formation of spindle during nuclear division
What is the conversion of mm to um ?
X by 1000
Mesosome defi.
- infold in wall of prokaryotes
- replication of DNA
Pili defi.
- hair like structures on the end of prokaryotes that allow them to stick to surfaces
Slime capsule defi.
- protects prokaryotic cells from physical and chemical attacks
Plasmid defi.
Circular molecule of DNA
What is the cell wall made from in prokaryotic cells ?
Peptidoglycan
What structures occur in prokaryotic cells but not Eukaryotic ?
Plasmid , pili, slime capsule, flagellum, mesosome
What is the name of a cell containing half the number of chromosomes of a normal body cell and give an example.
Haploid , sperm + egg cells
What is the name of the layer that surrounds an egg cell ?
Zona pullcida
What are the stages of fertilisation ?
- Sperm reaches ovum
- chemicals released from cells surrounding ovum triggering acrosome reaction
- acrosome swells, fusing with sperm cell surface
- digestive enzymes released
- digest through follicle cells and zona pullcida
- sperm fuses with ovum membrane
- nucleus enters ovum
- enzymes from lysosomes in ovum thicken zona pullcida (cortical reaction)
- nuclei of ovum + sperm fuse
Name the features of a sperm cell that make it efficient at its function
- Acrosome which contains digestive enzymes to break through egg wall
- many mitochondria from energy for swimming
- flagellum to swim
- haploid nucleus
Describe how cells become specialised
- signals cause different genes to become switched on and off
- only genes that are switched on will be transcribed
- different proteins that are transcribed the the cells different structure and functions
Totipotent definition
A cell that is able to differentiate into all cell types
Pluripotent definition
Can differentiate into most cells except placenta and umbilical cord
Describe how methylation affects DNA
Methylation is the addition of methyl groups to DNA preventing transcription factors from binding and the gene being transcribed
The gene is therefore “switched off”
Can be cause by environmental , lifestyle or age.
Describe how acetylation affects DNA and genes
Acetylation is the addition of an acetyl group to the host one tails
It prevents DNA winding as tightly around the histone exposing the DNA and genes “switch on”
This allowed the gene to be transcribed
Name the 3 parts of the cell cycle
interphase, mitosis, cytokinesis
what is the cell doing during interphase?
cell mass is increasing and normal cell functions are carried out
what are the 4 phases that occur in interphase?
G1, S, G2, G0
What happens in th s phase of interphase?
DNA in nucleus replicates
What happens in the G1 phase?
Protein synthesis
What hsppens in the G2 Phase?
Organelle replication, protein synthesis
How does a cell enter the G0 phase?
If a checkpoint ( one at g1 and one at g2) detects a fault in the replication of organelles and dna then the cell will be sent here to repair errors
What is the function of Cytokinesis? (How does it happen?
(animal)cell pinches at equatorial plate by filaments and cell contracts until split in two
(plant) a cell plate is synthesised between two nuclei
explain what happens during Prophase
- DNA condenses into chromosomes consisting of two identicle sister chromatids joined at a centromere
*centrosomes move to opposite poles of the nucleus - nuclear envelope breaks down
explain what happens during metaphase
- chromosomes line up along equatorial plate
- spindle fibres attatch to the centromere of the sister chromatids pulling them apart
describe what happens during Anaphase
Sister chromatids pulled apart at the centromere by shortening spindle fibres towards the centrosomes at opposite poles.
explain what happens during Telophase
- chromosomes begin to condense at opposite poles
- the nuclear envelope begins to reform around the chromosomes
- spindle fibres break down
why is mitosis important?
- growth of multicellular organisms(zygote needs it to form a baby)
- replacement and repair of damaged tissues
- Asexual reproduction
