Topic 6 - Cell Cycle Flashcards
Describe Stem cells
Unspecialised (undifferentiated)
Has the ability to differentiate into any type of cell
Found in bone marrow (adult) and embryo
Mitosis
Nuclear division
Cytokinesis
Cytoplasm division
3 parts of interphase
S. G1,G2
What is the importance of mitosis
Growth, repair, asexual reproduction
What is S phase
Synthesis phase - DNA is synthesised,semi-conservative replication occurs. Histones created
What occurs in G1
First phase of growth, cytoplasm / organelles increases
What occurs in G2
Second phase of growth, replicated DNA checked
When are the checkpoints?
In between G1 and S phase & G2 and metaphase
What occurs in interphase
Cell prepares to divide - G1, S, G2
What occurs in prophase
Chromosomes condense (shorter and fatter)
Nuclear envelope breaks down
What occurs in metaphase
Chromosomes (each with 2 chromatids) line up along the middle
Chromosomes attach to the spindle fibres
What occurs in anaphase
Centromeres divide, separating each pair of sister chromatids
Spindles contacts, pulling chromatids to opposite ends of the cell
What occurs in telophase
Nuclear envelope forms around each set of chromosomes
What occurs in cytokinesis
Mitotic index
Number of cells in the field/ total number of cells in the field of view
Cancer
Mutation
Uncontrolled cell division can lead to the formation of tumours and cancers.
In the blood/lymphatic system
Primary cancer VS secondary cancer
Primary- where the cancer begins
Secondary- where the cancer grows and spreads
What mutations cause cancer?
Tumour suppressor gene -if a mutation occurs the gene will be inactivated. No protein is produced
Cell divides uncontrollably.
Responsible for making proteins involved in slowing cell division or causing them to self-destruct (apoptosis)
Proto oncogene- stimulate cell division by producing proteins that make the cell divide. If a mutation occurs this gene can become overactive (stimulates the cell to divide uncontrollably- resulting in a tumour
Mutated proto-oncogene is called an oncogene
Methylation
Adding a methyl ( - CH3) group
DNA methylation
Control whether or not a gene is transcribed & translated.
The growth of tumours can be caused by abnormal methylation of certain cancer-related genes. Hyper methylation & hypomethylation
Length of time in phase
Observed number of cells at that stage/ total number of cells observed
X total length of cell cycle
Mitotic index
Number of cells in the field of view undergoing cell division / total number of cells in the field of view
