2.1 Cell Structure

Question 1

What are the three main ideas of the cell theory?

Answer 1

1. All living organisms are made up of one or more cells
2. Cells are the basic functional unit in living organisms
3. New cells are produced from pre-existing cells

Question 2

Prokaryotic vs Eukaryotic (Size)

Answer 2

Prokaryotic cells are smaller

Question 3

Prokaryotic vs Eukaryotic (Ribosomes)

Answer 3

Prokaryotic: 70 S
Eukaryotic: 80 S

Question 4

Prokaryotic vs Eukaryotic (Genome)

Answer 4

Prokaryotic: Circular DNA, suspended in the cytoplasm, not associated with histones
Eukaryotic: Linear DNA, found in the nucleus, associated with histones, DNA formed into chromosomes

Question 5

Prokaryotic vs Eukaryotic (Cell Division)

Answer 5

Prokaryotic: Binary Fission
Eukaryotic: Mitosis or Meiosis

Question 6

Prokaryotic vs Eukaryotic (Cell Wall)

Answer 6

Prokaryotic: Murein + Peptidoglycan
Eukaryotic: Found in plants (Cellulose) Found in fungi (Chitin)

Question 7

Prokaryotic vs Eukaryotic (Organelles)

Answer 7

Prokaryotic: NO membrane-bound organelles
Eukaryotic: many types of organelles including membrane-bound organelles (e.g. GA, ER, Mitochondria)

Question 8

Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells.

Answer 8

1. DNA in nucleus codes for a specific protein. (triplet code = amino acid)
2. Ribosomes on the rough endoplasmic reticulum synthesise the protein
3. Mitochondria produce ATP needed for protein synthesis
4. Golgi apparatus packages/modifies the protein by adding carbohydrates to make glycoproteins
5. Golgi vesicles transport proteins to cell-surface membrane
6. Vesicles fuse with the cell-surface membrane and leave cell via exocytosis

Question 9

Viruses are…

Answer 9

acellular and non-living.

Question 10

Why are there no organelles in the cytoplasm of an Red Blood Cell?

Answer 10

The cytoplasm is filled with haemoglobin.

Question 11

Many prokaryotic cells have…

Answer 11

1. One or more capsids
2. A capsule surrounding the cell wall
3. One or more flagella

Question 12

Structure and function of the cell-surface membrane.

Answer 12

F: All cells are surrounded by a cell surface membrane which controls the exchange of materials between the internal cell environment and the external environment
S: Consists of selectively-permeable phospholipid bilayer

Question 13

Structure and function of the nucleus.

Answer 13

S:
nuclear envelope- double membrane
nuclear pores- wholes within nuclear envelope
nucleoplasm- liquid w/in nucleus
nucleolus- where rRNA production occurs and makes ribosomes
F: site of DNA replication and transcription & contains genetic code for each cell

Question 14

Structure and function of mitochondria.

Answer 14

F:
- site of aerobic respiration in eukaryotic cells.
- ATP production
S:
- Surrounded by double-membrane with the inner membrane folded to form cristae, the matrix formed by the cristae contains enzymes needed for aerobic respiration, producing ATP.
mitochondrial DNA and ribosomes are also found in the matrix that are needed for replication.

Question 15

Structure and function of chloroplasts.

Answer 15

F: Site of photosynthesis in plants.
- The light-dependent stage takes place in the thylakoids
- The light-independent stage (Calvin Cycle) takes place in the stroma
S: Larger than mitochondria, also surrounded by a double-membrane.
Has membrane-bound compartments called thylakoids containing chlorophyll that stack to form structures called grana, which are joined together by lamellae (thin and flat thylakoid membranes)
Also contains small circular pieces of DNA and ribosomes used to synthesise proteins needed in chloroplast replication and photosynthesis

Question 16

Structure and function of the Golgi apparatus and vesicles.

Answer 16

F: modifies (adds carbohydrates to make glycoproteins and glycolipids) proteins and lipids and packages them into Golgi vesicles. The vesicles then transport the proteins and lipids to their required destination.
S: Folded membrane making cisternae

Question 17

Structure and function of lysosomes.

Answer 17

F: Release hydrolytic enzymes that can break down all types of biological polymers especially waste materials such as worn-out organelles.
- autolysis- break down dead cells completely
- exocytosis- release enzymes to outside of cell to destroy material
- digestworn out organelles for** reuse of material**
S: bags of distive enzymes

Question 18

Structure and function of ribosomes.

Answer 18

F: The site of translation (protein synthesis).
S: Freely found in the cytoplasm or on the surface of the rER in eukaryotic cells. Contains a large and small subunit.
- 80S ribosomes are found in eukaryotes
- 70S ribosomes are found in prokaryotes, mitochondria and chloroplasts

Question 19

Structure and function of the rough endoplasmic reticulum.

Answer 19

F: protein synthesis and where folding into secondary and tertiary structure occurs
S: folded membrane (cisternae) with ribosomes on cisternae

Question 20

Structure and function of the smooth endoplasmic reticulum.

Answer 20

F: **synthesis and storage of lipids and carbohydrates **.
S: folded membrane called cisternae

Question 21

Structure and function of the cell wall.

Answer 21

F: Provides structural support to cells (peptidoglycan → bacteria, cellulose → plants).
S: Formed outside the cell-surface membrane and are freely permeable to most substances.

Question 22

Structure and function of the cell vacuole. (Plants)

Answer 22

F:
- Keeps the cell turgid → provides supports breaks down
- isolates unwanted chemicals in plant cells,
- tonoplast controls what can enter and leave
- Temporary store of sugars and amino acids
S: Permanent and large. A sac in plant cells surrounded by the tonoplast (selectively permeable membrane)

Question 23

Structure and function of the cell vacuole. (Animals)

Answer 23

F: Helps sequester waste products.
S: Not permanent and small.

Question 24

In complex multicellular organisms, eukaryotic cells become … for specific functions.

Answer 24

specialised

Question 25

Structure of viruses.

Answer 25

Contain:
1. a nucleic acid core (their genomes are either DNA or RNA, and can be single or double-stranded)
2. a protein coat called a ‘capsid’

Question 26

Viruses are … meaning they can only reproduce by infecting living cells (host cells) and using their ribosomes to produce new viral particles

Answer 26

parasitic