Module 2 - structure of eukaryotic cells and prokaryotes Flashcards
4 marks
Describe the structure and function of the nucleus.
Structure
1. Nuclear envelope and pores/ Double membrane and pores
2. Chromosomes/ DNA with histones
3. Nucleolus
Function
4. Holds genetic material for polypeptides production
5. DNA replication occurs
6. Production of mRNA/tRNA
7. Production of rRNA/ribosomes
What does it mean if cells become flaccid or turgid
- If cells become turgid cells show water is absorbed by osmosis
- If cells become turgid cells show cells have a lower water potential
- If cells are not flaccid/plasmolysis cells show water is not lost by osmosis
2 marks
Give two features of all prokaryotic cells that are not features of eukaryotic cells
- No membrane-bound organelles
- Circular DNA
- Murein in cell wall
1 mark
Name the main polymer that forms the following cell walls.
Plant cell wall
Fungal cell wall
Cellulose (plants) and Chitin (fungi)
5 marks
Compare and contrast the DNA in eukaryotic cells with the DNA in prokaryotic cells.
Comparisons
1. Nucleotide structure is identical
2. Nucleotides joined by phosphodiester bond
3. DNA in mitochondria and chloroplasts same structure to DNA in prokaryotes
Compare
4. Eukaryotic DNA is longer
5. Eukaryotic DNA contain introns, prokaryotic DNA does not
6. Eukaryotic DNA is linear, prokaryotic DNA is circular
7. Eukaryotic DNA is associated with histones proteins, prokaryotic DNA is not
3 marks
Desribe 3 functions of the golgi apparatus
- Modifies and packages proteins
- Modifies and packages lipids
- Makes lysosomes
5 marks
Outline the similarities in, and the differences between, the structures of chloroplasts and mitochondria.
Similarities
1. Double membrane;
2. Both contain (circular) DNA;
3. Both contain ribosomes;
Differences
4. Thylakoids/lamellae/grana v cristae;
5. Stroma v matrix;
7. Starch grains v no starch grains;
2 marks
Suggest how Streptococcus bacteria with a thicker capsule are more likely to survive and so cause lung disease.
Phagocytes less likely to bind to murein in cell wall
This decreases pahgocytosis as theres more binary fission
Explain why the damage to the cells lining the ileum reduces the absorption of the products of digestion and why this reduces absorption of water
Surface area reduces
Less digestion enter cells
Water potential in cell doesnt decrease
So less water enter cells by osmosis
3 marks
Sodium ions from salt (sodium chloride) are absorbed by cells lining the gut. Some of these cells have membranes with a carrier protein called NHE3. NHE3 actively transports one sodium ion into the cell in exchange for one proton (hydrogen ion) out of the cell. Use your knowledge of transport across cell membranes to suggest how NHE3 does this.
- Co-transport
- Uses hydrolysis of ATP
- Sodium ion and proton bind to protein
- Protein changes shape to move sodium ion and proton across the membrane
Use your knowledge of membrane structure to explain the results in absorbance
* E – Ethanol, water and acid (greatest absorbance)
* F – Ethanol and water (2nd)
* G – Water (lowest absorbance)
- Higher absorbance indicates more pigment
- More membrane permeability results in more pigment release
- E and F greater than water because phospholipids dissolve in ethanol
- E greater than F because acid denatures membrane proteins
2 marks
Mikanolide is a drug that inhibits the enzyme DNA polymerase. Explain why this drug may be effective against some types of cancer.
- Prevents DNA replication / mitosis
- Nucleotides not joined together
5 marks
Describe the role of organelles in the production and release of enzymes by animal cells. Do not include details of transcription in your answer.
- DNA in nucleus codes for enzyme/protein production
- Ribosomes/rough endoplasmic reticulum produce proteins
- Smooth endoplasmic reticulum transports/modifies/processes protein
- Mitochondria produce ATP
- Golgi apparatus modifies and packages proteins
- Vesicles move protein to cell-surface membrane
2 marks
Determining the genome of the viruses could allow scientists to develop a vaccine.
Explain how
- The scientists could identify proteins that derive from the genetic code
- They could identify potential antigens to use in the vaccine
1 mark
Name two techniques the scientists may have used when analysing viral DNA to
determine that the viruses were closely related.
- The polymerase chain reaction
- Genetic fingerprinting
- Gel electrophoresis
- DNA/genome sequencing
Define resolution and outline how it is limited
Ability to distinguish between two points on an image
It is limited by the wavelength of the light/electrons
e.g. light microscope resolution is 200nm [half of the wavelength of light -400nm]
2 marks
Some proteins found inside the chloroplast are synthesised inside the chloroplast. Give one feature of the chloroplast that allows protein to be synthesised inside the chloroplast and describe one difference between this feature in the chloroplast and similar features in the rest of the cell.
- DNA
- Is not associated with histones proteins but nuclear DNA is
OR
Is circular but nuclear DNA is linear
OR
Is shorter than nuclear DNA - Ribosomes
- Are smaller than cytoplasmic ribosomes
Human breast milk is produced and secreted by gland cells. These gland cells have adaptations that include many mitochondria and many Golgi vesicles. The milk contains a high concentration of protein.
Explain the role of these cell adaptations in the production and secretion of breast milk.
- (Many mitochondria) release energy / ATP for movement of vesicles / active transport;
- (Many Golgi) vesicles transport protein / glycoprotein / milk to cell membrane / out of cell;
