Basic Cell Structure

Question 1

Label all structures the structures A-H seen in the image.

Answer 1

A: cytoplasm

B: lysosome

C: Golgi Complex

D: mitochondria

E: Endoplasmic reticulum

F: Nucleus

G: Plasma Membrane

H: Ribosome

Question 2

State the structure, function and disease associated with an error in the:

• Nucleus

Answer 2

Nucleus

Structure: Stained spherical structure that acts as the cell’s control centre.

Functions:

• DNA synthesis & repair,
• RNA synthesis,
• RNA processing & ribosome assembly.

Disease Associated:

• Alzheimer’s disease
• Parkinson’s disease
• Huntington’s disease

Question 3

State the structure and function of the following structures:

• Nucleolus
• Nuclear envelope

Answer 3

Nucleolus

Structure : Darker stained circular region with the nucleus (centre of nucleus)

Function : Ribosome synthesis

Nuclear membrane/envelope

Structure: Partially permeable double-membrane.

Function: Has nuclear pores for the passage of substances

Question 4

State the structure, function and the disease associated with an error in the:

• Cytoplasm

Answer 4

Cytoplasm

Structure: Contains enzymes, cellular organlles, and amino acids. Primarily made out of water.

Function: Cell morphology & movement.

Disease:

• Hunter’s disease
• Faybry disease
• Krabbe disease

Question 5

State the structure, function and the disease associated with an error in the:

• Ribosomes

Answer 5

Ribosomes

Structure: Tiny circular structures which:

• attahced to the rER
• lie freely in the cytoplasm

Function: Protein synthesis

Disease:

• Bone marrow failure
• Diamond blackfin anaemia
• Cancer
• Dyskeratosis congenita

Question 6

Distinguish between free and bound polyribosomes in terms of protein production.

Answer 6

• Free polyribosomes synthesise proteins which remain in the cytoplasm
• Bound polyribosomes show protein synthesis and segregation into the rough ER

Question 7

State the structure, function and the disease associated with an error in the:

• Plasma membrane

Answer 7

Plasma membrane

Structure: Partially permeable membrane that encloses contents of cells

Function:

• Regulates export of proteins (secretory vesicles)
• Transport of ions and small molecules

–

• Selective permeability
• Transport of materials along cell surface
• Endocytosis and exocytosis
• Intercellular recognition
• Barrier to water-soluble molecules

–

Disease:

• Alzheimer’s disease
• Sickle cell anaemia

Question 8

Describe the structure of plasma membranes.

Answer 8

• Composed of a phospholipid bilayer
• Hydrophilic heads, hydrophobic tails
• Associated membrane proteins: Integral and peripheral proteins

Question 9

Outline 4 features of the Fluid Mosaic Model

Answer 9

• Hydrophobic fatty acid tails in the middle
• Hydrophilic heads on the outside
• Membrane proteins: integral proteins, peripheral proteins
• Phospholipids form a bi-layer

Question 10

State the structure and function of the following:

• sER
• rER

Answer 10

Smooth ER

Structure : Network of tubes and flat curved sacs

Function:

• Detoxification reactions
• Fatty acid synthesis
• Lipid & steroid synthesis

Rough ER

Structure: Folded membranes studded with ribosomes

Function: Site of protein/membrane synthesis

Question 11

Describe the structure of the endoplasmic reticulum.

Answer 11

• ER membrane is continuous and encloses a single lumen
• sER does not have ribosomes attached
• rER has ribosomes attached

Question 12

State the structure and function of the following:

• Lysosome

Answer 12

Lysosome

Structure: Generated by the Golgi Apparatus

Funtion: Produces hydrolytic enzymes that aid in digesyion and excretion of substances

Question 13

Distinguish between primary and secondary lysosomes in terms of their formation and function.

Answer 13

Primary lysosome:

I. Formed from the Golgi apparatus

II. Does not release intracellular contents

Secondary lysosome:

I. Formed by the fusion of the primary lysosome and an endocytotic/phagocytotic vesicle

II. Releases intracellular contents/waste products

Question 14

State the structure and function of the following:

• Golgi complex

Answer 14

Golgi complex

Organelle that processes, modifies and repackages proteins produced in the rER for release at the cell membrane via secretory vesicles

Question 15

State the structure and function of the following:

• Microtubules
• Centriole
• Microvillii

Answer 15

Microtubules : part of the cell’s cytoskeleton, aid movement of substances through cytoplasm

Centriole: composed of two cylinders of tubules; essential to cell reproduction

Microvilli: projections which increase the cell’s surface area

Question 16

State the structure and function of the following:

• Microfilament
• Vacuole
• Cytoskeleton

Answer 16

Microfilament: provides support for the cell; sometimes linked to cell’s outer membrane

Vacuole: sac that stores and transport ingested materials, waste products and water

Cytoskeleton: internal framework of the cell, made up of microfilaments and hollow microtubules

Question 17

Describe the structure and function of mitochondria.

Answer 17

Mitochondrion

Double-membraned organlle where energy is released. Contains circular DNA, 70S ribosomes

• Site of ATP synthesis for metabolic reactions (oxidative phosphorylation)
• Metabolism of carbohydrates, amino acids, and nucleotides

Question 18

How are mitochondrias inherited?

Answer 18

Female lineage

Question 19

What are the two types of chromatin?

Answer 19

Euchromatin and Heterochromatin

Euchromatin

• does no stain strongly, lighter packaging

Heterochromatin

• stains more intensely, indicating tighter packing

Question 20

What is limit of resolution?

Answer 20

Limit of resolution – the minimum distance at which two objects can be distinguished

Question 21

Outline the general structure of prokaryotic cells.

Answer 21

• Prokaryotic cells have an external membrane but no internal membranes
• All the biochemical processes of the cell occur in the same compartment

Question 22

Identify 7 primary components of the prokaryotic cell

Answer 22

• Capsule
• Cell wall
• Plasma membrane
• Flagella
• 70s Ribosomes
• Nucleoid
• Pili

Question 23

Outline the general structure of a eukaryotic cell.

Answer 23

• Eukaryotic cells are compartmentalised by internal membranes.
• Hence, eukaryotic cells have a true nucleus and true organelles

Question 24

Identify 10 primary components of the eukaryotic cell.

Answer 24

• Plasma membrane
• Vacuole
• Nuclear envelope
• Nucleolus
• Chromosomes
• Lysosome
• ER (rER and sER)
• Golgi Complex
• Free ribosomes
• Mitochondria

Question 25

What is glycocalyx?

Answer 25

* The **glycocalyx** is the cell coat * It is made up of oligosaccharide and polysaccharide side chains on the outside of the plasma membrane

Question 26

Identify 4 functions of the cytoskeleton

Answer 26

* Determines the shape of animal cells * Ensures movement of cells * Structural support and movement of cell organelles * Provides the framework for moving and separating cells during cell division

Question 27

What are microtubules?

Answer 27

**Microtubules** are long hollow cylinders made of the protein tubulin

Question 28

Where are microtubules found?

Answer 28

Sites where structures are moved (i.e. nerve fibres, the mitotic spindle, cilia and flagella)

Question 29

How do bacterial, plant and mammalian cells differ in terms of: * Cell Wall

Answer 29

Plant: Cellulose cell walls Animals: None Bacterial: Murein cell walls

Question 30

How do bacterial, plant and animal cells differ in terms of: * Cell Nucleus

Answer 30

Plant: Controls activity of the cell. Each nucleus surrounded by a double membrane that has nuclear pores. Animal: Most have nucleus (except RBCs - refered to as anucleated cells). Some have \>1 nuclei (hepatocytes, refered to as coenocytes). Bacterial: None

Question 31

How do bacterial, plant and animal cells differ in terms of: * Plasmids

Answer 31

Plant: None Animal: None Bacterial: Present. Plasmid is a molecule of DNA that can r**eplicate independently**. **Double-stranded, circular and capable of replicating within a suitable host**.

Question 32

How do bacterial, plant and animal cells differ in terms of: * Mitochondria

Answer 32

Plant + Animal: Present. Outer membrane is smooth. Inner membrane folds to form **cristae**, increases the inner membrane's surface area. Site of ATP synthesis, metabolism of carbohydrates, amino acids & nucleotides Bacterial: None

Question 33

How do bacterial, plant and animal cells differ in terms of: * Ribosomes

Answer 33

Plant + Animal: 80S ribosomes. Site of protein synthesis. Can exist as free ribosomes or are attached to the rER. Made in the nucleolus. Bacterial: 70S ribosomes.

Question 34

How do bacterial, plant and animal cells differ in terms of: * Chloroplasts

Answer 34

Plant: Choloroplasts are present and contain the pigment chlorophyll. Animal: None Bacterial: None

Question 35

How do bacterial, plant and animal cells differ in terms of: * Permanent Vacuole

Answer 35

Plant: Large central permenant vacuole. Contains cell sap; water ions etc. Mains turgidity of the cell. Animal : None Bacterial : None

Question 36

Identify the following structures: * Heterochromatin * Zymogen granules * Nuclear envelope * rER

Answer 36

Question 37

Identify the following structure from this micrograph: * Cytoplasmic extension (CE) * Pinocytic vesicle (PV) * Golgi body (G) * Lysosome (L) * Nucleolus

Answer 37