Term
|
Definition
| 8 histone proteins wrapped by 2 winds of the DN double helix |
|
|
Term
| How large is the diameter of a double helix |
|
Definition
|
|
Term
| What are the 3 phases of interphase? |
|
Definition
|
|
Term
| What occurs in G1 and how long does is take? |
|
Definition
normal cell functions and cell growth
organelle duplication
protein synthesis
8-12hours |
|
|
Term
| What occurs in S and how long does is take? |
|
Definition
Duplicates chromosomes
DNA replication
Synthesis of histones
6-8hours |
|
|
Term
| What occurs in G2 and how long does is take? |
|
Definition
Protein synthesis
Further cell growth
Enzymes synthesised
2-5hours |
|
|
Term
| Which are the checkpoints? |
|
Definition
G1 (restriction point)
G2 checkpoint |
|
|
Term
| What is the final stage of the cell cycle? |
|
Definition
Mitosis: prophase, mataphase, anaphase, telophase
cytokinesis |
|
|
Term
| What did Meselon and Stahl's experiment prove? |
|
Definition
DNA replication is semi-conservative
2nd generation makes 1 hybrid and 1 light double heilx from one hydrid |
|
|
Term
|
Definition
1.helicase enzymes unwind strands and disrupt H bonds between bases
2.dna polymerase bind to exposed bases
3.dna polymerase can only move in 1 direction (w/ leading strand)
4.lagging strand moves in other direction
5.dna ligase splice two dna segments together
6.cell is ready for mitosis |
|
|
Term
|
Definition
| the division of the replicated dna into 2 daughter cells. |
|
|
Term
| Describe the events of early prophase |
|
Definition
chromosomes coil tightly
microtubules called spindle fibres extend between centrioles
nucleoli disappear |
|
|
Term
| Describe the events of late prophase |
|
Definition
nuclear envelope disappears
kinetochores (on centromere) attach to spindle fibres forming
chromosomal microtubules |
|
|
Term
| Describe the events of mataphase |
|
Definition
chromatids move towards and align at metaphase plate
centrosomes at opposite ends of cell |
|
|
Term
| Describe the events of anaphase |
|
Definition
centromeres split and separate the chromatids
mitotic spindle pulls the V shaped chromosomes to opposite ends of cell |
|
|
Term
| Describe the events of telophase |
|
Definition
nuclear envelope reforms
nuclei enlarge
chromosomes uncoil
2 identical nuclei in the cell
mitotic spindle will now break down |
|
|
Term
| Describe the events of cytokinesis |
|
Definition
division of cytoplasm into 2 daughter cells
cleavage furrow forms to pinch cytoplasm
not distinct from telophase, begins at anaphase |
|
|
Term
| What triggers a cell to divide? |
|
Definition
cell size
chemical signals
cyclins and cyclin dependent kinases |
|
|
Term
| how does cell size cause a cell to divide? |
|
Definition
as a cell grows, the surface area to volume ratio doesnt work in favour of diffusion. the nucleus needs more nutrients plus more waste removed.
therefore cell splits into 2. |
|
|
Term
| how does chemical signal/growth factor cause a cell to divide? |
|
Definition
| external signals can stimulate cell growth if there arent enough cells to fill our their roles |
|
|
Term
| What is required at G1 for the cell to progress |
|
Definition
| requires sufficient nutrients and signalling molecules present in extracellular environment. |
|
|
Term
| What happens if this isn't there? |
|
Definition
| they move to G0 where they can rest of leave cycle and terminally differentiate. |
|
|
Term
| What is required at G2 for the cell to progress |
|
Definition
| ensures all dna has been replicated and not damaged, otherwise mitosis will not be able to occur successfully. |
|
|
Term
|
Definition
regulatory proteins
fluctuating levels
increase during interphase
destroyed by proteases after miitosis |
|
|
Term
|
Definition
catalytic subunit
constant concentration in cells
inactive when cyclins not present
phosphorylate proteins responsible for cell division |
|
|
Term
| What role do cyclins and CDKs play? |
|
Definition
| they combine to form an activated heterodimer which is responsible for activating proteins that are required for cell division. |
|
|
Term
| Define cranial and caudal |
|
Definition
cranial = head
caudal = tail |
|
|
Term
| What are the 3 embryological planes? |
|
Definition
transverse
coronal
sagittal |
|
|
Term
| What are the two ways of dating pregnancy? |
|
Definition
|
|
Term
| What is menstural age dating? |
|
Definition
dates pregnancy from the woman's last menstural period
done by obstertricians and clinicians
pregnancy is divided into 3 equal trimesters |
|
|
Term
| What is fertilisation age dating? |
|
Definition
dates pregnancy from time of fertilisation
done by emryologists
pregnancy divided into 3 unequal parts |
|
|
Term
| How is the pregnancy divided in fertilisation age dating |
|
Definition
2 week: early development (cell division, pre-embryonic) period
3-9 weeks: embryonic (organogenesis) period
9+ weeks: foetal period |
|
|
Term
| When does ovulation occur? |
|
Definition
| 14 days into the menstural cycle |
|
|
Term
| What is the difference between menstural and fertilisation age? |
|
Definition
| menstural age is 2 weeks greater than the fertilisation age |
|
|
Term
| What causes Down's syndrome? |
|
Definition
Trisomy 21
abnormal number of chromosomes
21st pair are triplet |
|
|
Term
| What is Down's syndrome associated with? |
|
Definition
growth retardation
intellectual retardation
craniofacial abnormalities
congenital heart defects |
|
|
Term
|
Definition
environmental factors that cause birth defects.
sensitivity varies with the developmental stage at time of exposure. |
|
|
Term
| When is the highest risk of birth defect induced? |
|
Definition
|
|
Term
| How do infectious agents enter and what are the most common? |
|
Definition
across the placenta
TORCH:
toxoplasmosis
other (hep B, syphilis)
rubella (german measles)
cytomegalovirus (CMV)
Herpes complex virus (HDV) |
|
|
Term
|
Definition
drug used for morning sickness in 50's
shorted/absent limbs
now used to treat leprosy/HIV |
|
|
Term
| What is foetal alcohol syndrome |
|
Definition
clear relationship between alcohol consumption and congenital abnormalities
eg growth retardation and in severe cases intellectual disability |
|
|
Term
|
Definition
| the fusion of male and female gamete (23 chromosomes) fuse to form a zygote. |
|
|
Term
| What are the 3 layers of the uterus (out to in) |
|
Definition
perimetrium
myometrium
endometrium |
|
|
Term
| Where does fertilisation usually occur |
|
Definition
| ampulla of the uterine tube |
|
|
Term
| What is the fimbrae and what is its role |
|
Definition
| finger like projections from the infundibulum that sweep oocyte (egg) into uterine tube |
|
|
Term
| Where do sperm under capacitation (maturation) |
|
Definition
| female reproductive tract |
|
|
Term
| What is the acrosome reaction |
|
Definition
| sperm bind to zona pellucida and release enzymes to break down the zona. |
|
|
Term
| What is the zona reaction |
|
Definition
| zona pellucida secrete an enzyme to prevent further sperm from entering |
|
|
Term
| What happens to the zygote after fertilisation |
|
Definition
| zygote undergoes a series of cell divisions (cleavage) where the zygote remains the same size but the cells (blastomeres) get smaller |
|
|
Term
| How many cells are there at day 0, 1, 2, 3, 4 and 5? |
|
Definition
| 1, 2, 4, 8, Merula, Blastocyst |
|
|
Term
|
Definition
16-32 cell stage
inner cell mass: embryo proper (embryoblast)
outer cell mass: placenta (trophoblast) |
|
|
Term
|
Definition
| whena merula forms a fluid filled cavity |
|
|
Term
| What is an ectopic pregnancy |
|
Definition
| when implant occurs somewhere other than in the uterus |
|
|
Term
|
Definition
| When a blastocyst is fully formed it contacts the endometrium and attaches |
|
|
Term
| how do trophoblasts develop? |
|
Definition
-trophoblast cells divide rapidly and layer becomes thick
-plasma membranes disappear and are replaced with a multinucleated cytoplasm (called syncytical trophoblast)
-remaining trophoblasts become cytotrophoblasts |
|
|
Term
| How is the amniotic cavity formed? |
|
Definition
=syncytical trophoblast continues to spread
-Eroded uterine glands release nutrients absorbed by synctical trophoblast providing energy for early embryo formatio- |
|
|
Term
| What do embryoblasts differentiate into |
|
Definition
| epiblasts and hyperblasts |
|
|
Term
|
Definition
| hormone secreted by syncytitrophoblasts that helps maintain endometrium and maternal immunotolerance. Pregnancy indicator |
|
|
Term
|
Definition
| formation of a third layer of cells between the superficial and deep layers of the inner cell mass. Forms 3 germ layers. |
|
|
Term
| What makes up the bilaminar disc? |
|
Definition
| consists of hypoblast and epiblast cells |
|
|
Term
| When does the groove form? and what is its role |
|
Definition
15 days
primitive streak defines major body axis |
|
|
Term
| What happens once the groove has formed? |
|
Definition
| cells of the epiblast migrate inwards towards the streak. They detach from the epiblast and slip beneath it. |
|
|
Term
| What is the hypoblast replaced by? |
|
Definition
| a new layer (definitive endoderm) |
|
|
Term
| What happens after endoderm is formed? |
|
Definition
| epiblast cells move down and form middle mesoderm layer. |
|
|
Term
| What happens after mesoderm is formed? |
|
Definition
Mesoderm becomes highly organised:
-lateral plate mesoderm
-intermediate mesoderm
-paraxial mesoderm
and then a notochodal process
Remaining epiblast becomes ectoderm. |
|
|
Term
| What does the embryonic ectoderm surround? |
|
Definition
| amniotic cavity with the primitive groove |
|
|
Term
| What does the embryonic endoderm surround? |
|
Definition
|
|
Term
| What cell produces the 3 germ layers and what are they |
|
Definition
| Epiblast produces ectoderm, mesoderm and endoderm |
|
|
Term
| What does the ectoderm eventually develop into |
|
Definition
| outer layer of skin, hair, lining of nose and mouth and nervous system |
|
|
Term
| What does the mesoderm eventually develop into |
|
Definition
|
|
Term
| What does the endoderm eventually develop into |
|
Definition
| digestive tract, respiratory tract, liver and pancreas |
|
|
Term
| In which direction does development occur |
|
Definition
| cranial region before caudal |
|
|
Term
| What are the two consequences of abnormal gastrulation? |
|
Definition
|
|
Term
|
Definition
'mermaid syndrome' occurs when insufficient mesoderm is formed in the caudal region of the embryo.
Causes abnormalities of urogenital system and lower limbs |
|
|
Term
|
Definition
| remnants of primitive streak may persist and give rise to a tumour (sacrococcygeal teratoma). Most common newborn tumour (1/40000 and 80% female). Most neonates diagnosed are fine. |
|
|
Term
|
Definition
first event in CNS development
initiated by signals from the notochord that cause induction
overlying ectoderm thickens and forms neural plate |
|
|
Term
|
Definition
| thickened area of cells formed at cranial end of embryo |
|
|
Term
| Describe the formation of the neural tube |
|
Definition
| lateral edges of the neural plate elevate and fuse to form neural tube. Fusion beings in neck of embryo and continues cranially and caudally. |
|
|
Term
| What do neural crest cells contribute to |
|
Definition
| formation of the peripheral nervous system |
|
|
Term
| What does the notochord do |
|
Definition
| initiates and organises the formation of vertebrae from somites |
|
|
Term
| What does paraxial mesoderm divide into? |
|
Definition
| segments called somites which the notochord induces differentation of |
|
|
Term
| What are the somites and what they become |
|
Definition
sclerotome > bone and cartilage
myotome > skeletal muscle
dermatome > dermis |
|
|
Term
| How is the vertebral body and vertebral arch formed? |
|
Definition
| sclerotome cells surround the notochord to form the vertebral body and the neural tube to form the vertebral arch. |
|
|
Term
| What do abnormal inductions of the sclerotomes result in? |
|
Definition
|
|
Term
|
Definition
| spine does not close causing a gap and dimpling of skin, hair sometimes sprouts |
|
|
Term
|
Definition
| protusion of the meninges through a gap in the spine |
|
|
Term
| What is myelomeningoecele |
|
Definition
| spinal cord and meninges protude from childs back there is no skin covering it so high infection chance. |
|
|
Term
| When is neuralation complete |
|
Definition
-when anterior (day 25) and posterior (day 28) neuropores fuse
-cranial end of the neural tube forms the brain and caudal end forms the spinal cord |
|
|
Term
| What is the result of failure of the anterior neuropore to fuse? |
|
Definition
-anencephaly
-forebrain does not form
-brainstem present
-still birth/short life |
|
|
Term
| What is the result of failure of the posterior neuropore to fuse? |
|
Definition
-Rachischisis
-spinal cord does not fuse properly > paralysis
-open neural tube prevents formation of vertebrae
-flat plate of neural tissue is exposed at birth |
|
|
Term
| Name 3 neural tube defects and how they can be reduced |
|
Definition
Rachischisis
Anencephaly
Spina bifida
FOLIC ACID |
|
|
Term
| what is the '4th germ layer' and what does it do |
|
Definition
| neural crest cells separate from the neural tube and migrate and disperse widely and differentiate into a variety of structures throughout the body |
|
|
Term
| What are neural crest cells derivatives |
|
Definition
-sensory ganglia
-autonomic ganglia
-meninges of the brain and spinal cord
-Schwann cells
-satelite cells
-melanoblasts
-suprarenal medulla
-several skeletal and muscular components in the head |
|
|
Term
| What is neurofibromatosis |
|
Definition
| genetic disorder caused by mutation of neurofibromin 1 (NF1 gene) |
|
|
Term
|
Definition
| tumour suppressor gene that is 'switched off' in neurofibromatosis leading to increased cell division |
|
|
Term
| What occurs in the 4th week of development |
|
Definition
the embryo undergoes a rapid development in size and shape
trilaminar disc undergoes folding craniocaudally and laterally |
|
|
Term
| What causes embryonic folding |
|
Definition
differential growth of the amniotic sac and yolk sac
amniotic sac grows much more |
|
|
Term
|
Definition
-amniotic sac expands and pushes down left and right edges of the embryonic disc
-lateral plate mesoderm splits into a visceral layer and a parietal layer
-starts to pinch the endoderm and pinches yolk sac
-left and right sac fuses and surrounds embryo |
|
|
Term
|
Definition
| pushes head and tail together as amniotic cavity expands |
|
|
Term
|
Definition
| lateral folding fails to fuse in thoracic region leaving the heart outside the body 1/5million |
|
|
Term
|
Definition
| lateral folding fails to fuse in abdominal region leaving intestines outside the body wall (not covered by a membrane) |
|
|
Term
|
Definition
| biological aging where cells stop diviing/proliferating and become more susceptable to death |
|
|
Term
| What are the 3 causes of ageing |
|
Definition
Increased production of free radicals
Replicative cell senescence (Hayflick phenomenon)
Telomere shortening |
|
|
Term
| What are free radicals and the role they play |
|
Definition
reactive oxygen species
highly damaging to DNA, proteins etc
scavenged by antioxidants
reducing ROS production increases lifespan |
|
|
Term
| how many times can one cell divide |
|
Definition
|
|
Term
| What are telomeres and their signifigance |
|
Definition
telomeres form the ends of human chromosomes and synthesised by telomere
telomeres shorten with each round of cell division
exposed chromosome ends activate p53 dependent cell arrest (halts cell cycle) |
|
|
Term
|
Definition
the death of cells/tissues from disease/injury.
uncontrolled and triggers inflamatory response |
|
|
Term
|
Definition
'programmed cell death'
tightly controlled and does not elicit inflammatory response |
|
|
Term
| Describe the stages of apoptosis |
|
Definition
cell shrinks and chromatin condenses (ATP dependent)
forms apoptotic bodies with functioning organelles
adjoining healthy cells phagocytose apoptotic bodies |
|
|
Term
| Describe the stages of necrosis |
|
Definition
cell, organelles swell. Chromatin in nucleus clump. ATP independent.
loss of membrane integrity
nucleus swells
LEAKS |
|
|
Term
| What is apoptosis mediated by |
|
Definition
caspases
there are 12 in humans
two types: initiator and executioner |
|
|
Term
| How is apoptosis triggered? |
|
Definition
1.apoptotic stimuli
2.causes cleavage of initiator procaspases
3.converting them into active initiator caspases
4.which cleave exectuitioner procaspases
5.converting them into active executioner caspases
6.which cleave specific cellular targets within the cell to trigger apoptosis |
|
|
Term
| Describe the extrinsic plasma membrane apoptosis |
|
Definition
1.pro-apoptotic receptor activated by pro-apoptotic ligand
2.ligand binding causes receptors to cluster and form a complex
3.when a complex is activated, pathway works as intrinsic |
|
|
Term
| Describe the extrinsic mitochondria apoptosis |
|
Definition
1.stimulus causes release of cytochrome C from mitochondria
2.cytochrome c activates Apaf 1 and converts dATP to dADP
3.leads to Apaf 1 assembling into a heptamer called apoptosome
4.apoptosome recruits and activates the initiator caspase 9, resulting in activation of execuitioner caspases and apoptotis. |
|
|
Term
| What regulates the release of cytochrome c |
|
Definition
|
|
Term
| What do Bcl-2 family proteins do? |
|
Definition
| regulate the mitochondrial pathway for apoptosis |
|
|
Term
| What do BH123 proteins do and give examples |
|
Definition
form a pore to release cytochrome c =. this occurs when bh123 proteins are activated after a death signal within a cell.
bax and bak |
|
|
Term
| What do bh3 proteins do and give examples |
|
Definition
BH3 proteins stimulated bh123 homo-dimerisation (direct activators)
BH3 proteins can repress the pro-survival function of Bcl-2 proteins. |
|
|
Term
|
Definition
tumour supressor protein
encoded by tp53 gene
promotes apoptosis
malfunction or loss promotes cancer |
|
|
Term
|
Definition
1.dna damage
2.rise of p53 in cell
3.trigger Bax channel in mitochondria
4.release of cytochrome c
5.induce production of caspase 9
6.induced apoptosis
7.damaged dna cell does not divide |
|
|
Term
| What diseases are caused by excessive apoptosis |
|
Definition
stroke
heart attack
neuronal diseases
Alzheimers and parkinsons |
|
|
Term
| What diseases are caused by reduced cell death |
|
Definition
cancer
-Fas mutation
-BCl2 mutations
-p53 mutations |
|
|
Term
| What does cancer result from |
|
Definition
| abnormal proliferation of cells and decreased apoptosis |
|
|
Term
| What tissue is affected by carcinoma |
|
Definition
|
|
Term
| What tissue is affected by sarcoma |
|
Definition
| connective tissue and muscle |
|
|
Term
| What tissue is affected by myeloma |
|
Definition
|
|
Term
| What tissue is affected by lymphoma |
|
Definition
| other: wbc's nervous system cells etc |
|
|
Term
| how can mutations cause cancer |
|
Definition
1.mutations that activate proto-oncogenes to oncogenes
2.inactive tumour suppressor genes |
|
|
Term
| What environmental factors cause cancer |
|
Definition
1.uv light/radiation
2.chemicals (cigarette smoke)
3.viral infections (papilloma virus, hep B&C) |
|
|
Term
|
Definition
promotes abnormal proliferation of cells
present in retroviruses (as proto-oncogenes acquired from eukaryotes and mutated to oncogenes)
result from mutations of proto-oncogenes |
|
|
Term
|
Definition
-encode proteins that regulate cell growth and differentation
-involved in signal transductions
-examples: growth factors, g proteins, protein kinases
-become oncogenes when mutated |
|
|
Term
| what happens when proto-oncogene RAS is mutated |
|
Definition
goes from G->C switches this protein on to become permenantly
active, resulting in uncontrolled cell proliferation |
|
|
Term
|
Definition
physical examination
mammography
bood markers
faecal occult in blood test
mri
main: biopsy
stages 1-4 |
|
|
Term
|
Definition
surgery
radiotherapy
chemotherapy |
|
|
Term
| what does radiotherapy do |
|
Definition
kills cells that have spread to adjacent local/regional tissues:
ionising radiation kills cancer cells
damages healthy tissue
more localised than chemo |
|
|
Term
| what does chemotherapy do |
|
Definition
kills cancer cells through the body:
anti-cancer or cytotoxic drugs
targets all cells
unpleasant side effects
high does chemo often proceeds stem cell transplantation for haemotological cancers |
|
|
