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Top2 BCM > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

Haemoglobin is what?

A

Iron containing protein complex
2 copies of alpha and 2 copies of beta found in red blood cells of vertebrates, primary function to transport oxygen around the cell

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2
Q

Temporal gene regulation is?

A

When a gene is expressed at a specific time in development/growth
Q

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3
Q

Spatial gene regulation is?

A

When a gene is only expressed in specific cell

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4
Q

What is spatiotemporal expression?

A

Expresison of genes within specific tissues/cells of an organism at specific times during development/growth

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5
Q

What is an enhancer?

A

Regulatory DNA sequence to which regulator proteins, trans-acting factors bind. Increasing the rate of transcription of a gene

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6
Q

What is an insulator?

A

Regions of chromatin that act as boundaries and prevent euks and prevent euk gene regulatory proteins from influencing distant genes

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7
Q

Thalassaemia is what?

A

An inherited form of anemia caused by faulty synthesis of hemoglobin

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8
Q

Anemia is what

A

Decrease in number of RBCs or less than the normal quantity of hemoglobin in the blood

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9
Q

What is the difference between regulated gene expression in terms of single and mutlicelled organisms?

A

Single celled, changes in gene expression in repsonse to external cues but all cells aare the same.
Multi celled, different cell types can differ in the genes they express

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10
Q

Why can cells have the same genome but are different in shape, size and function?

A

Some genes are needed by all cells such as B actin, which are the essential genes. Other genes are only expressed accordingly to the behaviour and function of those cells

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11
Q

How to prove that all genes are present in all somatic cells?

A

Fuse donor epithelial cells with enucleated egg cell to produce a reconstructed zygote which can still form into an embryo and a living mamals

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12
Q

What does pluripotent mean?

A

The iPS cells (induced pluripotent cells) have potential to give rise to any cell type

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13
Q

What are the 3 diff ways in which a repressor can bind and inhibit transcription?

A

a) Competitive binding where the activator binding site and repressor binding site overlaps. So the activator protein and repressor protein compete to bind but therepressor protein ends up binding with the activation surface coming into repulsion with the repressor surface
b) Masking the activation surface, so the activator and repressor have their relevant sites but the surface of the activator is masked by the surface of the repressor
c) direction interaction with the general transcription factors. The repressor binds to its relevant site but the surface then binds to the general transcription factors such as TFIID

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14
Q

Genes are often influenced by what?

A

Multiple activators and repressors

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15
Q

Twist is an activator that controls what? and expresses where and what

A

Many other genes. It is expressed in the ventral parts of the embryo and activates the expression of rho

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16
Q

What are the twist and snail binding sites?

A

Twist is CAYATGT

Snail is MMRCAGWT

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17
Q

Rho is an example of what type of repression?

A

Compettivie

Enhancer region of rho has binding sites for twist and snail

18
Q

Twist is what and snail is what?

A

Twist is activator

Snail is repressr

19
Q

Snail is expressed where and how

A

Also in a ventral band but in a more restricted region within the twist region

20
Q

The target gene rho is activated by what and repressed by what? so how is it expressed?

A

Activated by Twist, repressed by snail.
Rho only expressed when twist is on and snail isnt
Twist - SNail

21
Q

What is EMT

A

Epithelial mesenchymal transition

When cells lose their epithelial characteristics and become migratory

22
Q

Tumours are caused by what?

A

Mutations that can change expression of genes controlling proliferation and cell death. Further mutations can result in inappropriate expressions of genes like twist, twist can then turn on many other target genes which can cause benign tumor cells to under EMT and become metastatic

23
Q

How many oxygen molecules can hemoglobin bind?

A

4 oxygen mmolecules

24
Q

Quickly describe the cycle of hemoglobin in terms of tissues and lungs

A

In the lungs where oxygen is more, hemo binds the oxygen and co2 is decreased. pH is also increased.
In the tissues, O2 is lower and CO2 is increased so O unbinds from hEMO

25
Q

What are the human globin genes and describe its prevelance over the course of life?

A

Epsillon, Gy and Ay, delta and beta
Epsillon is prevalent in embryos
The gammas are prevalent in fetal development and then slowly develop into delta genes which is no longer as prevalent in adulthood. The beta genes increase from fetal to adulthood

26
Q

The beta globin cluster is conserved how and contains what elements?

A

Evolutionarily conserved

Contains LINE and SINE elements

27
Q

Describe the expression of the globin genes through development in the megaloblast, macrocyte and normocyte and name their relevant organs

A

Megaloblast, in the yolk sac and liver. High amounts of alpha + gamma, average levels of epsillon but decreases in liver, gamma increases in liver. Beta levels are low in yolk and liver.

Macrocytes are mainly in liver and spleen. High alpha, high gamma, no epsillon, low beta

Normocytes, in bone marrow, high alpha, high beta, low gamma, low delta

28
Q

y globin is still a type of what globin but in different form?

A

Beta

29
Q

So describe the structure of foetal hemo and adult hemo?

A

Foetal is 2alpha + 2 gamma

Adult is 2alpha+2 beta

30
Q

Why does foetal hemo have a different composition?

A

Binds to oxygen with greater affinity, giving the foetus better access to oxygen from the mothers bloodstream

31
Q

Expression of Beta globin genes is an example of what regulation?

A

Spatiotemporal gene reg

32
Q

What is the LCR?

A

An enhancer sequence
Locus control region
Enhances expression by interacting with regulatory factors present at the promoters of the globin genes.

33
Q

given that enhancers can have an influence from a long way away, such as the LCR. How is this influence confined to the right gene?

A

Insulator elements create loops in chromsomes which limit the region an enhancer can affect

34
Q

What are the insulator sequences that stops LCR activating other genes?

A

HS5 and 3’HS1

35
Q

What are the defects in the human globins for
alpha thalassaemia
beta thalassaemia

A

Alpha - defect in alpha globin , 2

Beta -defect in beta, 1

36
Q

Sickle cell anaemia

a) Inherited how?
b) What is the effect?
c) difference betwene RBC and sickle?
d) the advantage of sickle RBC

A

a) Autosomal recessive
b) limits oxygen reaching organs so there is organ damage. Low RBC so anemia. Intense pain when sickle RBCs get stuck in blood vessels due to the stiff and angular shape which gets stuck in small capillaries
c) RBCs live for 120 days.
Sickle only lives for 10 to 20 days
d) Resistant to malaria

37
Q

The beta globin gene has how many exons and codes for what protein?

A

3 exons

146 amino acid protein

38
Q

SCD results from what

A

A single nucleotide pairing. AT sequence is otherway around on the strands. Glutamic acid is turned into valine. Valine is mutant

39
Q

B Thalassaemia

a) B0 and B+ refer to what mutations?
b) what are most of the B globin gene mutations?

A

a) B0 is no beta globin produced
B+ mutation result in a diminished but not absent quantity of beta globin.
b) point mutations that can interfere with gene transcription, splicing, create premature stop codons or interfere with translation

40
Q

Beta thalassemia major is what?

A

Refers to a severe clinical phenotype that occurs when patients are homozygous or compound hetero for severe beta chain mutation. Patients display severe transfusion dependent anaemia, child would die by age 5 and appear normal at birth.

41
Q

Beta thalassemia intermedia is what?

A

In between clinical phenotype with hetero genetic mutation that still allow for some beta chain production

42
Q

Beta thalassemia minor?

A

Mild clinical phenotype when one normal copy of the beta globulin gene is present

Top2 BCM (9 decks)

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