Block C/E Flashcards
Whats a practical definition of genetic mapping in humans?
The identification of polymorphic markers with alleles that co-segregate with disease in extended families
How are BACs used in the Human Genome Project?
To hold fragments of genomic DNA as part of the physical mapping process
LD blocks are made up of _______
haplotypes
Apoptosis is triggered by_______
Caspases
What are the 2 classes of apoptotic caspases.
Initiator and executioner caspases
How are initiator caspases activated
They are activated by dimerisation through adaptor proteins binding to the adaptor binding domain.
How are executioner caspases activated
Once the protease domain is cleaved, the executioner goes through an activating conformational change
How does an executioner caspases control apoptosis
They cleave a variety of key proteins, leading to controlled cell death
Which type of caspases do extrinsic and intrinsic apoptosis activate
Executioner caspase
Desrcibe extrinsic cascade
Extracellular proteins bind to cell surface death receptors to trigger the extrinsic pathways of apoptosis
Describe intrinsic cascade (5 marks)
Cells release the mitochondrial protein, cytochrome c. Cytochrome C activates Apaf1. Assembly of 7 activated Apaf1 proteins form a complex called apoptosome. Apoptosome recruits caspase-9. Activation of caspase-9, cleaves and activates executioner caspases.
Give 3 reasons why cells would activate apoptosis from within a cell.
-DNA damage
-cellular stress
-in response to a developmental cue
Name the regulatory proteins that specifically regulate the intrinsic pathway and how (2 marks)
Bcl2, controls the release of cytochrome c.
Define stem cells
An immortal, unspecialised cell
Name the stem cell based on the description. Zygote created by fertilisation. Generates all cells inc placenta
Totipotent
Name the stem cell based on the description. Generates all cells apart from placenta cells.
Pluripotent
Name the stem cell based on the description. Produces Red Blood Cells and all White Blood Cells
Multipotent
Name the stem cell based on the description. Produces sperm cells
Unipotent
How do we grow Embryonic Stem cells. (3 marks)
To keep it in an undifferentiated state, we need to provide it with differentiation inhibitors and factors that promote proliferation.
Name a known factor for differentiation inhibition in mice.
Leukaemia inhibitory factor (LIF)
State 4 problems with using stem cells as regenerative medicine (4 marks)
-injecting ES cells might cause cancer
-is it histocompatible, and will you have to use immunosupressors
-cells must be able to differentiate in a controlled manner
-is stem cells from donor safe and disease free
Give 2 pros and 2 cons of using iPS cells.
Pros:
-easier to create
-doesnt require human oocyte
Con:
-not clear if reprogramming is complete
-cells could cause cancer
Describe the multiple hit theory (3 marks)
Its now believed that the development of tumours require 5-8 independant hits that occur over time. A single cell layer undergoes a mutation that either enhances cell proliferation or decreases cell death. Proliferation hastens the next step of tumour progression by increasing the size of the population thats at risk of another mutation.
Describe the altered metabolism in cancer cells.
Tumour cells generally produce adundant lactate, because of its increased rate of glycolysis.
Define oncogene
Mutated gene that has the potential to cause cancer
Define proto-oncogene
A cell that plays a role in regulating normal cell division.
What is p53 and how can it contribute to tumour development. (3 marks)
p53 is a nuclear transcription factor with a pro-apoptotic function. levels of p53 increase in genetically damaged cells, this causes apoptosis. however a loss of p53 function will allow genetically damaged cells to escape apoptosis and proliferate
Which protein helps to configure duplicated chromosomes for seperation
Condensin
Which protein helps form multi-subunit protein complexes and functions, structurally, to hold sister chromatids together
Cohesin
Which protein catalyses the cleavage and seperation of cohesins
Seperase
What protein is activated by the release of cytochrome c from mitochondria in the intrinsic pathway of apoptosis.
Apaf1
Fill out the sentence describing gene amplification in cancer. A _____ protein is greatly ______
A normal protein is greatly overproduced.
