Chapter 2 Cell Structure and organisation

Question 1

Define nucleus

Answer 1

An organelle that contains genetic information.

Question 2

What are the different membranes surrounding the nucleus and what are there functions?

Answer 2

The nucleus is bounded by two membranes : the nuclear envelope with pores that allow the passage of large molecules and the outer membrane is continuous with the endoplasmic reticulum .

Question 3

What are the 3 principles of cell theory?

Answer 3

• All living organisms are composed of one or more cells.
• The cell is the basic unit of life.
• Cells can only arise from pre-existing cells.

Question 4

What is the mitochondria?

Answer 4

The site of ATP production during aerobic respiration.

Question 5

What are the components of the mitochondria? (3)

Answer 5

• The mitochondria has two membranes.
• An organic matrix containing compounds such as lipids and proteins.
• 70S ribosomes and a small circle of DNA which enable it to create proteins and to self replicate.

Question 6

What is a cristae?

Answer 6

The inner membrane of the mitochondria which fold to provide a large surface area for the attachment of enzymes for respiration.

Question 7

What is a chloroplast?

Answer 7

The site of photosynthesis within a cell.

Question 8

What are the components of a chloroplast? (2)

Answer 8

• Chloroplasts are surrounded by two membranes.

* They contain 70S ribosomes and a small circle of DNA to enable self replication.

Question 9

What are the stroma?

Answer 9

The stroma are fluid filled sacs in the chloroplasts and contains lipids and starch used for photosynthesis.

Question 10

What are thylakoids?

Answer 10

Thylakoids are located within the stroma and are small flattened sacs which stack together to make a granum.

Question 11

What is a granum and what is its function?

Answer 11

Granums are stacks of thylakoids and contain photosynthetic pigments such as chlorophyll.

Question 12

What is the endoplasmic reticulum?

Answer 12

A system of double membranes which allows the transport of materials through the cell

Question 13

What is the Rough ER?

Answer 13

An ER with ribosomes on the outer surface and transports the proteins that are made there.

Question 14

What is the Smooth ER?

Answer 14

Membranes that lack ribosomes and is associated with the synthesis and transportation of lipids.

Question 15

What is a Golgi body?

Answer 15

A complex of vesicles and folded membranes involved in intracellular transport.

Question 16

What are the functions of the Golgi body? (5)

Answer 16

• produces secretory enzymes packed in the vesicles
• secretes carbohydrates
• produces glycoproteins
• transporting and storing lipids
• forming lysosomes and containing digestive enzymes.

Question 17

What are lysosomes?

Answer 17

Small temporary vacuoles surrounded by a single membrane.

Question 18

How are lysosomes formed?

Answer 18

Lysosomes are formed by being pinched off the Golgi body.

Question 19

What are the functions of lysosomes? (2)

Answer 19

• They contain and isolate digestive enzymes from the cell.

* They release these enzymes when the cell needs to recycle worn out organelles.

Question 20

What are Centrioles?

Answer 20

Centrioles are two rings of microtubules making hollow cylinders positioned at right angles to one another.

Question 21

What are the functions of the centrioles? (2)

Answer 21

• Helps division in animal cells.

* During cell division they organise the microtubules that make the spindle that separate the chromosomes.

Question 22

What is a vacuole?

Answer 22

Most plant cells have a large permanent vacuole which consists of cell sap and bounded by a membrane (the tonoplast). The vacuole contains glucose, amino acids, minerals, vitamins and pigments.

Question 23

What is the material in the nucleus called and what is its function?

Answer 23

The granular material in the nucleus is nucleoplasm. It contains chromatin which is made of coils of DNA bound to protein.

Question 24

What is a nucleolus and what is its function?

Answer 24

The nucleolus is a spherical body within the nucleus. They are the sites of formation of rRNA and ribosomes.

Question 25

What are the functions of the cell wall in plant cells? (3)

Answer 25

* Transport * Support the cell * Communication between cells

Question 26

What is the plasmodesmata?

Answer 26

Fine strands of cytoplasm that extend through the pores in plant cell walls, connecting the cytoplasm of one cell with that of another.

Question 27

Give one example of how organelles are interrelated.

Answer 27

Protein synthesis: | Translation in nucleus, mRNA travels to ribosome for transcription, packaged at the Golgi body.

Question 28

Define prokaryote and give an example.

Answer 28

A single celled organism lacking membrane-bound organelles , with its DNA free in the cytoplasm. E.g bacterium.

Question 29

Define eukaryote and give an example.

Answer 29

An organism containing cells that have membrane-bound organelles with its DNA in chromosomes within a nucleus.

Question 30

What is a ribosome chemically composed of?

Answer 30

``` Ribosomal RNA (rRNA) Protein ```

Question 31

What is the process of differential centrifugation?

Answer 31

Cellular material is ground up with an isotonic sucrose buffed solution over ice. The solution is spun in a centrifuge where dense organelles are separated. The remaining solution is spun at an increasingly faster speed and the less dense organelles separate and can be removed. Separating organelles is called subcellular fractionation.

Question 32

Which two types of large molecules are always present in virus particles?

Answer 32

Nucleic acid | Protein

Question 33

Define tissue

Answer 33

A group of cells working together with a common function, structure and origin in the embryo.

Question 34

What are the 4 types of tissue?

Answer 34

Epithelium Muscle Connective Nerve

Question 35

What are the characteristics and functions of epithelial tissue?

Answer 35

Epithelial tissue forms a layer of cells and covers all body organs and lines all glands. The cells are formed on a basement membrane. Epithelium tissue often has protective or secretory functions.

Question 36

What is a basement membrane of epithelium tissue made up of?

Answer 36

Collagen and protein

Question 37

What are the key characteristics of simple cuboidal epithelium and give an example of where it can be found?

Answer 37

Cells have a cube shape and the tissue is one cell thick. | It can be found in the kidney tubules and thyroid gland.

Question 38

What are the key characteristics of columnar epithelium and give an example of where it can be found?

Answer 38

Elongated cells with cilia. | It lines the trachea and oviducts.

Question 39

What are the characteristics of Squamous epithelium and where can it be found?

Answer 39

Flattened cells on a basement membrane. | They form the walls of the alveoli in the lungs.

Question 40

What are the 3 types of muscle tissue?

Answer 40

Smooth Striated/skeletal Cardiac

Question 41

What are the characteristics of smooth muscle?

Answer 41

* Spindle shaped cells. * Cells have a single nucleus. * Involuntary control, stimulated by nerve impulses and hormones.

Question 42

What are examples of where smooth muscle can be found?

Answer 42

The walls of blood vessels (arteries) and in the digestive tract (gut)

Question 43

What are the characteristics of striated/skeletal muscles?

Answer 43

* Bundles of long thin cells containing proteins (actin and myosin). * Cells are multinucleate * Voluntary control, stimulated by nerve impulses.

Question 44

Where are striated/skeletal muscle found?

Answer 44

Bones | Biceps

Question 45

What are the characteristics of cardiac muscle?

Answer 45

* Myogenic (does not need a nerve impulse to trigger contraction, it is started in the muscle itself) * Appears striated * Cells have single nucleus * Does not fatigue

Question 46

Where is cardiac muscle found?

Answer 46

In the heart

Question 47

What are the characteristics of connective tissue and what is its function?

Answer 47

It contains collagen fibres allowing it to be tough with great tensile strength but inelastic. The function of connective tissue is to connect, support and separate tissues and organs.

Question 48

Where can connective tissue be found?

Answer 48

Blood Bone Cartilage