Cell Cycle, etc Flashcards
What is the cell theory?
- All living things are made of one or more cells
- Cell is the basic unit of life
- New cells arise from existing cells
Purpose of cell cycle
- New cells needed
- Replace dead cells
- Regular cell death
- Asexual reproduction
Process of Binary fission
- Bidirectional replication of DNA
- DNA moves to poles
- Cell elongates and cleavage furrow forms
- Cytokenisis - cell divides.
Compare Binary fission to Mitosis
- Only 20 mins
- Much faster
- Asexual reproduction
- Single strand DNA splits into 2
- Undefined processes.
What is Chromatin made of
- Tightly wounded histones and proteins.
Characteristic of homologous chromosomes
- Same gene located on same loci of each pair.
Which genders DNA determines sex of offspring?
MALE
How many genes does X and Y chromosomes carry?
X = up to 1500
Y = up to 300
What is the default gender?
Female
Define Karyotype?
Collection of chromosomes in an inidivudal
Characteristics of chromosome pairs
- Different size to others
- Different no. genes to other pairs
Define Locus
Location of individual genes
cell cycle checkpoint??
G1- PREPARATION FOR DNA REPLICATION/ grows
S– DNA REPLICATION (error= apoptosis)
G2- PREPARW FOR MITOSIS
M- Check if chromosomes r allighnednproperly in metaphase (error = apoptosis)
G0- if cell is under stress/ delay , pause and apoptosis or improve
Dna replicarion
- Double helix unzips
- Polymerase adds nucleotides to strand.
Centrosomw
Where microtubules are produced. Has two centrioles made of 9 ringed microttubules.
Prophase
Chromosomes condense
Nuclear envelope disappears
Centrosomes move to opposire poles
Apoptosis
Programmed cell death
Undegoes during wnd of cell life
Dysfunctional or damaged
Lipid based hormones
LIPID BASED HORMONES SUCH AS STEROID HORNONES TRAVEL THEOUGH BLOOD INTO CARRIER PROTEIN
Protein based hormone
Such as amine hormone or peptide hornone travel freely in blood but cant pass phospholipid bikayer unless receptor
Stages og apoptosis
Caspaces are triggered
Divide (cleave) Intracellular materials are digested
Cell shrink - nucleus and organelles
Blebing - cytoskeleton dies, cell weakens and splits into small vesicles called apoptotic bodies
Phagocytosis - apoptotic bodies get engulfed snd digested by phagocytes
Extrinsic pathway
Signalling molecules attack to desth receptors on plasma membrane
Procadpaces activated
Cell undergoes apoptosis
Reason for extrisnicnpathway
- no longer needed
- replaced by new cell
- nonfunctional
Intrinsic pathway
Cell undergoes stress and mitochondria detects
Pores on cristae of mitochondria release cytochrome c
Cytochrome c activates caspaces in cytoplasm
Cell undergoes apoptosis
Reason for intrinsic
Dna damage, virus infection, uv radiation, etc
Necrosis
Cell dies due to external factors like injury blood loss or disease, typically cell bursts and affects surrounding organelles causing inflammation
Checkpoint malfunction
Enzymes operate checkpoints
Enzymes can be prevented from functioning
Enzyme can be stimulated to stay in one state permanently
Both causes unmonitored cell division and cancer
Cancerous cells
Gene controlling cells cell cycle gets mutated
Metastasis- invading tissues
Proliferation- send signals to grow and divide
Evading growth suspension- escape stop growing signals
Differentiation
Process of less specialised cell becomes more sepcific im structure and function
Stem cells
Undifferentiated cells becoming specialised
- totipotent- all differentiated cwlls in organism
- pluripotent- differentiate into a type of 3 germ layer cell (blastocyst)
Induced pluripotent stem cell (ipscs)
Adult somatic cell reprogrammed yo return to undifferentiated embryonic state
Totipotent
Cell that can develop into any type of cell
Zygote, embryonic cells
Multipotent
Differentiate intk limited cell type in same tissue
Blood cells, bone cells
Pluripotent
Differentiate into all cell types except for embryonic tissue
Idpscs, blastocyst
