page 5 Flashcards
(22 cards)
apoptosis
It is used during early development to eliminate unwanted cells
- programmed cell death (natural occurring)
- occurs through shrinking of cytoplasm
- often beneficial
- requires ATP
necrosis
- accidental cell death (caused by toxin, trauma)
- occurs through swelling of cytoplasm
- harmful to organism
- does not require ATP
Stages of embryonic development
Fertilised egg (day 1), morula (day 3), blastocyst (day 5), gastrula (day 12), embryo (week 3) and foetus (week 8)
Fertilised egg
also known as zygote
Morula
when zygote undergoes mitosis to become two cells it becomes a morula
blastocyst
as the cell becomes to specialise in the uterus it becomes a blastocyst. Has one layer
gastrula
has three different layers of cell
internal checkpoints
Internal checkpoints are used to repair the cycle if a mutation occurs.
They are active in G1, G2 and metaphase.
G1 checkpoint
G1 checkpoint check if there are adequate resources for the cell to divide such as neotides and energy to copy the dna. Also if the cell is large enough to divide and if the nuclei has not been damaged
G2 to Mitosis checkpoint
G2 checkpoint checks for adequate resources such as proteins require for mitosis and if the DNA and chromosomes have all been replicated without mistake or damage.
Metaphase checkpoint
M checkpoint determines if all the spindle fibre have been correctly attached to the sister chromatids and the chromosomes are aligns at the equator.
external cell cycle control
environment factors that have an effect
Benign neoplasm
- Cell divide uncontrollably but not as rapid as malignant
- organism controls the growth of the neoplasm to an extent and don’t penetrate the blood or lymph vessels
- does not destroy the surrounding tissues and grow in a capsule
Malignant neoplasm
- cells divide uncontrollably
- uncontrolled cell growth breaks out of capsule
- neoplastic cells can spread to other tissues
- destroys the surrounding tissues
Proto-oncogenes
are a group of normal genes involved in the regulation of cell division. Mutation of this gene can change them into a oncogenes which induce uncontrolled cell division leading to neoplasms
tumor -suppressor genes
Group of genes that code protein involved in the slowing down of cell division, the repair of DNA
environment factors
such as exposure or radiation can damage dna
Carinogens
A carcinogen is a substance or mixture that causes cancer. there are three types (cancer causing agents): chemical physcial and biological
Nondisjunction
a pair of homologous chromosomes has failed to separate at anaphase
chromosmal changes
deletion, duplication, inversion, and translocation.
polyploid
possessing more than two complete sets of chromosomes
Aneuploidy
presence of one or more extra chromosomes or the absence of one or more chromosomes
