Cells - Module 2

Question 1

Describe the process of translation.

Answer 1

In translation, the tRNA will travel to the cytoplasm to retrieve an amino acid. It will then bind to the ribosome which has the mRNA. The anti-codon of the tRNA will match the codon of the mRNA and then facitilite the formation of peptide bonds between the amino acids. A site is where tRNA enters the ribosome, P site is where it holds the growing polypeptide chain and E site is where tRNA exits.

Question 2

Where does translation occur?

Answer 2

All translation occurs on free ribosomes.

Question 3

Define the terms promoter, tata box binding protein, upstream, 5 to 3, template strand, RNA polymerase, and polyadenylation signal.

Answer 3

Promoter is the start line of a specific sequence in DNA. Tata box binding protein is a type of protein helps the binding of RNA polymerase to the promoter. Upstream is the 5’ end of the coding strand (beginning) where the promoter is located. RNA polymerase is the enzyme that synthesis RNA. Polyadenylation signal occurs when the end of copying the DNA template strand.

Question 4

Describe the difference of apoptosis and autophagy.

Answer 4

Apotosis is orgasmed cell death and autophagy occurs when damaged organnels are degraded. Lysosomes are involved in autophagy.

Question 5

What is the function of tumour suppressor genes and give examples.

Answer 5

They inhibit uncontrolled cell division and promote cell cycle regulation. However, when they become mutated, they cannot control the cell regulation so it increase proliferation. Cell regulation is the process for checking damage to the cell. p53, BRCA1, andBRCA2.

Question 6

What are Phosphatases?

Answer 6

Phosphatases catalyze the process of dephosphorylation, which is the removal of phosphate groups from proteins.

Question 7

Difference between mitosis and meiosis?

Answer 7

Mitosis produces two genetically identical diploid daughter cells. Meiosis results in four genetically diverse haploid gametes.

Question 8

Where does transcription occur?

Answer 8

Nucleus

Question 9

What is phosphofructokinase?

Answer 9

In order for glycolysis to progress to the pyruvate oxidation stage, there must be high concentrations of AMP (which occurs when the cell requires aerobic respiration to produce ATP). This stimulates the action of phosphofructokinase.
Glycolysis does not progress to the pyruvate oxidation stage of cellular respiration if there are high concentrations of citrate and ATP (because these are the products of cellular respiration, and high concentrations indicate that sufficient cellular respiration is occurring). High concentrations of citrate and ATP therefore inhibit phosphofructokinase.

Question 10

What is the difference between protooncogenes and oncogenes?

Answer 10

Proto-ocogenes are normal genes that play essential roles in regulating cell growth, division, and differentiation. Onocogenes are genes that are mutated proto-oncogenens. Oncogenes promote uncontrolled cell division and can lead to the development of cancer.

Question 11

What is the endomembrane system?

Answer 11

Network of MEMBRANE BOUND organelles. It includes Nucleus
Endoplasmic Reticulum (smooth and rough)
Golgi apparatus
Lysosomes NOT mitochondria and ribosome.

Question 12

What is the difference between eukaryotic and prokaryotic cells.

Answer 12

Eukaryotic has membrane bound organelles whereas prokayotic does not, and has no nucleus. Think prokaryotic as bacteria.

Question 13

What are integral proteins vs pheprial proteins?

Answer 13

Integral proteins are embedded inside the plasma membrane, whereas phepiperal are associated with the membrane but not embedded. Example: transmembrane proteins as integral proteins.

Question 14

What do plasma membrane do?

Answer 14

1. Cell transport (letting ions in and out)
2. Enzyme bidning
3. Singal transduction
4. Cell - cell recognition (Use of glycoproteins, where proteoglycans are a special type of glycoproteins)
5. Intercellular joining such as adherens junctions
6. Attachment to the cytoskeleton.

Question 15

What does dynamic mean in terms of the plasma membrane.

Answer 15

Dynamic means that plasma membrane is ALWAYS changing, active and adaptable. The plasma membrane is not a rigid structure but a mosaic of molecules bobbing in
a fluid bilayer of phospholipids. It it cell specific as well.

Question 16

What are the structures of the nucleus and the function.

Answer 16

Nuclear envelope, continous with the ER. Nucleolus which is rRNA production and rRNA is part of the ribosomes which are the entry and exit of molecules. Chromatin is the material that makes up the DNA.

Question 17

How much can DNA stretch out to and how does it fit in the nucleus?

Answer 17

Approximativly 2 metres but it fits because it is wrapped around twice of 8 histone proteins, which make up 1 nucleosome. Multiple nucleosomes are known are chromatin.

Question 18

What is the difference between free ribosomes and attached to the ER.

Answer 18

free in the cytoplasm - making proteins to be used in cytosol (non-endomembrane destinations)
OR attached to the RER making non-cytosolic proteins/endomembrane.

Question 19

What is cisternae?

Answer 19

This complex is made up 3-20 flattened
membranous sacs called cisternae

Question 20

Difference between the cis and trans side of the Golgi?

Answer 20

Cis receives proteins from the ER and trans ships it to in out out of the cell (plasma membrane), lysosomes, Secretory Vesicles.

Question 21

What are lysosomes and their function?

Answer 21

There are vesicles from the Golgi apparatus that contain digestive enzymes to break down any pathogens / damaged cells. They go through processes of autophagy (digestion of damaged organelles) and autolysis (digestion of entire cells). membrane proteins pump H+ in to maintain acidic pH.

Question 22

What are the key structures of mitochondria?

Answer 22

Outer, inner, cristae and matrix.

Question 23

Explain difference of filaments : microfilaments, intermediate and mircrotubels.

Answer 23

Microfilaments: Smallest, consits of actin molecules twisted around each other in 2 long chains. Found in the lining of the cell, Bear tension and weight by anchoring cytoskeleton to plasma membrane proteins, and is dynamic. 7nm.
Intermediate: Bear tension THROUGHOUT the cell, and most permanent (least dynamic). 8-10 nm.
Microtubles: Composed of Dublin dimers (alpha and beta), 15nm diameter Support and movement of cilia /flagella, dynamic.

Question 24

How is energy made?

Answer 24

Though the hydroliss of ATP to ADP, meaning using h2o to break the bonds of ATP which releases energy.

Question 25

What are the 4 steps of production of ATP from glucose.

Answer 25

1. Glycolsis 2. Pyruvate oxidation 3. Citric acid cycle 4. Electron transport chain

Question 26

Do all somatic cells divide and give examples of cells that do not divide.

Answer 26

Many, but not all, some a lot more than others! Caridomyocytes, neurones, Myocytes (skeletal cells), Erythrocytes (red blood cells).

Question 27

Describe interphase.

Answer 27

Interphase is a phase of the cell cycle where somatic cells reside most of the time. It is spilt into 3 parts : G1 where cellular activities are occurring, S where DNA replication occurs strands are separated at the hydrogen bonds holding the nucleotides together new strand of DNA is synthesized opposite each of the old strands and Growth or Gap Phase 2 checks for correct DNA synthesis prepares for the Mitotic Phase (synthesis of the proteins and enzymes required, gathering of reactants), replication of centrosomes is completed.

Question 28

What type of cell are in the GO phase?

Answer 28

Nerve cells and the Go phase is the phase where the cell in not dividing, its just resting. Happens after the cell cycle.

Question 29

Explain pMAT.

Answer 29

Prophase - Centrosomes move to opposite sides of cell, miotic spindle forms by microtubules, Chromosones condense inside the nucleus, nuclear envelope breakdowns so the centrosomes can access the condensed chromosomes. 2. Metaphase- Condensed chromes line up, the spindle fibres are attached to the chromosones 3. Anaphase is where chromosomes separate, one sister chromatid goes on one side and the other sister chromatid goes on the other side. 4. Telophase is where chromosomes decondese in chromatin, nuclear envelope forms and cleavage furrow

Question 30

What controls the miotic cell division?

Answer 30

CHECKPOINTS 1. G1 Checkpoint = Checks for cell damage, nutrition and cell size. If the cell is not right, it will go to Go. 2. M checkpoint= metaphase, are all spindle fibres attached to the chromosomes?

Question 31

What is the end result of mitosis?

Answer 31

Two, each genetically identical to the parent cell, w the same number of chromosomes.

Question 32

Explain the difference of mitosis and meiosis in terms of how they replicate DNA.

Answer 32

1. In prophase, homologous chromosomes pair up (2 sister chromatids) and form a tetrad. However, in prophase of mitosis, chromosomes condense.

Question 33

When do homologous chromosomes separate during Anaphase?

Answer 33

Homologous chromosome pairs are separated during Anaphase I, not 2.

Question 34

What are the two ways where altered DNA sequence can have effects on protein?

Answer 34

1. Germline which can be passed onto future generations. 2. Local/somatic which affects during cell division.

Question 35

Do mutations always have an affect on the structure and function of protein.

Answer 35

No, mutations can affect the structure and function of a protein but not always.

Question 36

What are the two different types of scale alterations and what is the difference between them?

Answer 36

1. Small scale which affects one or few nucleotides and large scale which affects chromosomal

Question 37

Types of small scale alterations

Answer 37

1. Substitution 2. Insertion/deletion

Question 38

Explain a silent mutation and why it has no impact on the nucleotide.

Answer 38

Silent mutations are a type of substitution mutation but the amino acid that it codes for is the same as the original amino acid that it codes for. Therefore, no change in protein.

Question 39

What type of mutation would be missense?

Answer 39

It's a substitution mutation where changes result in a different code for the amino acid.

Question 40

What is the type of mutation where there is a stop codon right in the middle of the DNA sequence?

Answer 40

Nonsense mutation.

Question 41

What is insertion/ deletion mutations and how does it cause frameshift mutations.

Answer 41

Insertion where an extra nucleotide is added and it changes the whole sequence, sometimes having a pre-mature codon in it as well. Deletion mutations occur when nucleotides are deleted, resulting in protein is completely altered from point of frameshift, can have catastrophic effect.

Question 42

Where is frameshift mutations the worst?

Answer 42

When the frameshift happened early in the DNA sequence , it would be worse because it would change the ENITRE sequence.

Question 43

Does 3 nucleotide mutation result in frameshift mutations.

Answer 43

No

Question 44

Where would the mutations would NOT have an impact?

Answer 44

Promoter / upstream region,

Question 45

What is another name for template strand?

Answer 45

Non-coding strand.

Question 46

Give an example of a missense mutation.

Answer 46

Sickle cell amnia where a single nucleotide substitution causes a change in the amino acid that it codes for. The sickle-shaped red blood cells become stiff and sticky, which makes them less flexible and unable to pass easily through small blood vessels. This then changes the shape of the red blood cell, making it sickle shaped cell (rigid), disrupting the blood flow and oxygen delivery.

Question 47

Describe glycolysis and where does it occur?

Answer 47

Glycosis is the first step of ATP production. It occurs in 2 steps: Investment phases where 2ATP molecules are invested/used to break glucose apart (6carbon chain molecule). The broken glucose results into 2, 3 pyruvate carbon molecules. Lysis is the process of splitting glucose apart. Then there is the energy payoff phase where 4ATP are produced, but a net total of 2atp because 2ATP were used in the start. 2 NADH is produced. This occurs in the cytosol and NO oxygen is required.

Question 48

Describe pyruvate oxidation and where does this occur?

Answer 48

Pyruvate oxidation occurs in the mitochondrial matrix and requires oxygen. It produces Acetyl CoA which is important for cKerbs cycle. It produces 2NADH per glucose and 2 CO2 per glucose. NO ATP.

Question 49

What is the input and output for glycosis?

Answer 49

Input= 6 carbs glucose Output = 2, 3carbon pyruvate molecules and 2NADH, 2ATP

Question 50

What is the citric acid cycle and where does this occur?

Answer 50

Citric acid cycle is when the Acetyl CoA undergoes a series of reactions and produces 6NADH, 2FADH2, 2ATP, 4CO2, per glucose molecule and requires oxygen. This occurs in the matrix.

Question 51

What is electron transport chain?

Answer 51

So the 2FADH2 and 6NADH are electron donors and are oxidised. Donated electrons move from protein to protien, lose energy. This part occurs in the inner mitochondrial membrane.The energy used is used to pump H + ions in the inter membrane space. Oxygen “pulls” the electrons down the chain, and is then the final electron acceptor where it is reduced to water, meaning oxygen is required.

Question 52

Chemiosmosis

Answer 52

The H plus ions rush down to the matrix due to their concentration gradient , causing the enzyme ATP synthase to rotate / turn. The rotation of the ATP synthase turbine enables the phosphorylation of ADP to generate ATP, which creates 26/28 ATP per glucose. It does require oxygen.

Question 53

What is a proton graident?

Answer 53

When H plus ions build up in the inter membrane space.

Question 54

What blocks the passage of electrons to O2 which results in death of cell.

Answer 54

Cynaide, a toxic molecule.

Question 55

What are other things other than glucose that can generate ATP?

Answer 55

Fats, proteins and more complex carbohydrates generate ATP also

Question 56

What is diabetes?

Answer 56

Diabetes Mellitus : the ability to produce or respond to the hormone insulin is impaired results in abnormal metabolism of carbohydrates and elevated levels of glucose in the blood

Question 57

Difference between type 1 and type 2?

Answer 57

Type1 Body does not produce insulin, as beta cells of pancreas are destroyed, often this is autoimmune, or genetic or through environmental factors and type 2 is Body produces insulin, but receptors are non functional (insulin resistance).

Question 58

What are the two symptoms of diabetes?

Answer 58

significantly increased hunger * significant weight loss. This is because when they eat, the body can't get glucose into the cells because there's no insulin.

Question 59

What is a codon?

Answer 59

A codon is a set of three nucleotides that codes for 1 amino acid.

Question 60

Are calcium ions are a second messenger?

Answer 60

Yes