2.1.1 - Cell Structure (set A - Euckaryotic Cell Organelle)

Question 1

Define a prokaryotic organism?

Answer 1

Prokaryotes are organisms whose cells lack a nucleus and other organelles, prokaryotes are divided into two distinct groups: the bacteria and the archaea

Question 2

Define eukaryotic organisms?

Answer 2

A eukaryote is any organism consisting of one or more cells that contain DNA in a membrane-bound nucleus, separate from the cytoplasm - examples are plant, animal, fungi and protists

Question 3

Explain the structure of the nucleus, make reference to all key parts?

Answer 3

Large organelle containing a dense structure called the Nucleolus and chromatin (DNA) and is surrounded by the semipermeable Nuclear Envelope, a structure composed of an inner and outer nuclear membrane which contain a number of nuclear pores

Question 4

Explain the main function of the nucleus?

Answer 4

• Controls the cells activities by controlling the transcription of DNA (instructions needed for making proteins), gene expression mitosis and semiconservative replication
• contains DNA coiled around chromatin into chromosomes

Question 5

Explain what the plant cell wall is?

Answer 5

Rigid structure that surrounds plant cells, made of cellulose microfibrils for mechanical support

• plasmodesmata form part of apoplast pathway to allow molecules to pass between cells

Question 6

Explain the function of the cell wall?

Answer 6

The cell wall gives the cell structure, which prevents it from changing shape. It also offers a small level of added protection.

Question 7

Explain what the plasma cell surface membrane is?

Answer 7

The membrane found on the surface of animal cells and the inside the cell wall of plant cells - the cell membrane consists of a lipid bilayer that is semipermeable - composed of proteins and lipids

Question 8

Explain the function of plasma cell surface membrane?

Answer 8

Regulates the movement of substances into and out of the cell - has receptor molecules on it which respond to chemicals like hormones

Question 9

What is the lysosome?

Answer 9

A round organelle suspended by a membrane, with no clear internal structure - acts as rubbish bin as they break down excess or worn-out cell parts with digestive enzymes

Question 10

What is the function of the lysosome?

Answer 10

Contains hydrolytic enzymes kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of the cell

Question 11

What are ribosomes?

Answer 11

very small organelle that either floats free in the cytoplasm or are attached to the rough endoplasmic reticulum - made up of proteins and RNA (not surrounded by a membrane)

Question 12

What is the function of ribosomes?

Answer 12

The site where proteins are made

Question 13

What is the rough endoplasmic reticulum (RER)?

Answer 13

The RER is a membrane bound organelle located near the nucleus It is made up of thin, fluid filled membranes that are stacked together (cisternae) and is covered with ribosomes

Question 14

What is the function of rough endoplasmic reticulum (RER)?

Answer 14

Folds and processes proteins that have been made at ribosomes - the site of protein synthesis

Question 15

What is the smooth endoplasmic reticulum (SER)?

Answer 15

Has the same structure as the rough endoplasmic reticulum but does not have ribosomes

Question 16

What is the function of the smooth endoplasmic reticulum (SER)?

Answer 16

Responsible for carbohydrate and lipid synthesis, and storage

Question 17

What is the vesicle?

Answer 17

A small fluid-filled sac in the cytoplasm, surrounded by a membrane

Question 18

What is the function of the vesicle?

Answer 18

Transports substance in and out of the cell (via the plasma membrane) and between organelles

Question 19

Where are vesicles formed?

Answer 19

some are formed by the Golgi apparatus or the endoplasmic reticulum while others are formed by the plasma membrane

Question 20

What are mitochondria?

Answer 20

Usually oval-shaped and have a double membrane - the inner one if folded to form structure called cristae inside is the matrix which contains enzymes involved in respiration

Question 21

what is the function of mitochondria?

Answer 21

The site of aerobic respiration here ATP is produced - they’re found in large numbers in cells that are very active and require lots of energy such as muscle,brain or liver cells

Question 22

What is the Golgi apparatus?

Answer 22

A group of fluid-filled membrane-bound, flattened sacs which have vesicles at the edges

Question 23

What is the function of the Golgi apparatus?

Answer 23

• Processes and modifies new lipids and proteins and packages them into vesicles
• makes lysosomes
• allows internal transport

Question 24

What are chloroplast?

Answer 24

Small, flattened structures found in plant cells they are surrounded by a double membrane - have thylakoid membranes inside which are stacked up in some parts of the chloroplast to form grana which are linked together by lamellae

Question 25

What is the function of chloroplasts?

Answer 25

The site where photosynthesis takes place - some parts of photosynthesis happens in the grana, other parts happen in the stroma

Question 26

What are stoma?

Answer 26

located in the chloroplast and responsible for some photosynthesis - is a thick fluid

Question 27

What are centriole?

Answer 27

Small, hollow cylinders made of microtubules found in animal cells, but only some plant cells located in the cytoplasm

Question 28

What are 3 functions of centriole?

Answer 28

- They engage in the arrangement of mitotic spindles during cell division - organises the microtubules in the cytoplasm - regulate the position of the nucleus and other organelles in the cell.

Question 29

What are cilia?

Answer 29

Small ‘hair like’ structures found on the surface membranes of some animal cells - have an outer membrane and a ring of nine pairs of protein microtubules inside with two microtubules in the middle

Question 30

What is the function of cilia?

Answer 30

Microtubules allow the cilia to move - the movement is used by the cell to move substances along the cell surface - located in the bronchus and moves microbes and debris up and away from the lungs

Question 31

What are flagellum?

Answer 31

Flagella on eukaryotic and prokaryotic cells are like cilia but longer, stick out of the cells surface and are surrounded by plasma membrane - have two microtubules in the centre surrounded by nine pairs around the edge

Question 32

What is the function of flagellum?

Answer 32

The microtubules contract to make the flagellum move - for example the tail on sperm cells allow it to swim to the egg

Question 33

What are cytoskeletons?

Answer 33

The cytoskeleton is a network of proteins that forms the internal framework for the cell

Question 34

What are the three components of the cytoskeleton?

Answer 34

- microfilaments - microtubules - intermediate fibres

Question 35

What are microfilaments?

Answer 35

Fibres made from the protein ‘actin’ they are responsible for movement of the cell and cytoplasm during cytokinesis

Question 36

What are microtubules?

Answer 36

Formed by protein ‘tubulin’, they polymerise to form tubes that determine the shape of the cell

Question 37

What are intermediate fibres?

Answer 37

Gives strength to cells and helps maintain integrity

Question 38

What is the structure of the cellulose cell wall?

Answer 38

Cellulose is a long chain of beta-glucose. Beta-glucose molecules are linked by glycosidic bonds to form linear cellulose chains that are unbranched. Microfibrils are strong fibres that are made of many cellulose chains that are held together by hydrogen bonds.

Question 39

What is the function of the cellulose cell wall?

Answer 39

- gives the plant mechanical strength - gives the plant support and its shape - contents of the plant can ‘push’ against the cell wall (turgid cell), giving the plant support

Question 40

What is the structure of the large permanent vacuole?

Answer 40

Single membrane bound (membrane called a ‘tonoplast’) contains cell sap - has selectively permeable barrier - membrane allows control of certain molecules

Question 41

What is the function of large permanent vacuole?

Answer 41

- stores cell sap - supports herbaceous plants by making cells turgid - sugar and amino acids act as temporary food source

Question 42

What are 5 features of prokaryotes?

Answer 42

- extremely small cells, smaller then eukaryotes - DNA is circular and free in the cytoplasm - no nucleus - no membrane-bound organelles or mitochondria - small ribosomes

Question 43

What are 4 features of eukaryotes?

Answer 43

- larger cells - DNA is linear and enclosed inside the nucleus - mitochondria and other membrane-bound organelle present - large ribosomes

Question 44

how are mitochondrion adapted for increased reactions?

Answer 44

Have crista which are finger like folds in the inner membrane of a mitochondrion, its purpose is to increase the surface area to allow for more reactions to take place

Question 45

What are cisternae and which organelle of a cell are they located?

Answer 45

Stacks of membrane bound (fluid filled) sacs which form sheets found in the endoplasmic reticulum and Golgi apparatus

Question 46

What are membranes, what is their function?

Answer 46

Membranes are selectively permeable and control the movement of substances into and out of the cell and organelles