Ultrastructure of cells

Question 1

Nucleolus

Answer 1

Dense ,spherical structure
area within the nucleus and is responsible for the production of ribosomes.
Composed of RNA and proteins. RNA is used to produce rRNA. This combines with proteins to make the ribosomes necessary for protein synthesis

Question 2

Chromatin

Answer 2

A mass of genetic material composed of DNA and proteins (histones) that condense to form chromosomes.

Question 3

Nuclear Envelope

Answer 3

Surrounds the nucleus with pores to allow large molecules /substances to move in and out of the nucleus
Double membrane protects nucleus from damage in the cytoplasm

Question 4

Histone

Answer 4

A histone is a protein that provides structural support to a chromosome. In order for very long DNA molecules to fit into the cell nucleus, they wrap around complexes of histone proteins, giving the chromosome a more compact shape.

Question 5

Structure of the nucleus

Answer 5

Largest organelle containing the nucleoplasm with chromatin and the nucleolus

Question 6

Nucleus function

Answer 6

holds genetic information that is responsible for the coding of proteins.
DNA directs the synthesis of all proteins required by the cell - in this way dan controls the metabolic activities of the cell as many of these proteins are enzymes necessary for metabolism to take place.

Question 7

Cytoskeleton

Answer 7

cells contain a network of fibres of protein , provides mechanical strength and stability to the cell by maintaining its shape (internal framework)

Question 8

what a thee three components of the cytoskeleton ?

Answer 8

microfilaments
microtubules
intermediate fibres
centriole

Question 9

microfilaments

Answer 9

contractile fibres formed from protein actin
responsible 4 cell movement and cell contraction during cytokinesis ( process where cytoplasm of single eukaryotic cell is divided to form two daughter cells).

Question 10

centriole structure

Answer 10

cylinder shaped organelle made of microtubules around a cylindrical centre

Question 11

centriole function

Answer 11

involved in cellular replication and organising mitotic spindle

Question 12

microtubule structure

Answer 12

globular tubular proteins polymerise to form tubes to form scaffold-like structures that determines shape of cell

(linear polymers of tubular which is a globular protein)

Question 13

microtubule function

Answer 13

move vesicles ,granules organelles like mitochondria , and chromosomes via special attachment proteins
spindle fibres composed of microtubules

Question 14

intermediate fibres

Answer 14

give mechanical strength to cells and maintain their integrity

Question 15

Endoplasmic reticulum

Answer 15

is a interconnected network of membranes enclosing flattened sacs called cisternea .
Connected to outermembrane of the nucleus

Question 16

Smooth endoplasmic reticulum structure

Answer 16

interconnected network of membranes enclosing flattened sacs called cisternae that do not contain ribosomes

Question 17

Smooth endoplasmic reticulum function

Answer 17

lipid and carbohydrate synthesis, and storage

Question 18

Rough endoplasmic reticulum structure

Answer 18

interconnected network of membranes enclosing flattened sacs called cisternae that has ribosomes bound to the surface of the outer layer

Question 19

Rough endoplasmic reticulum structure

Answer 19

process and transport proteins

Question 20

golgi apparatus structure

Answer 20

stack of flattened membrane-bound sacs called cisternae

Question 21

gold apparatus function

Answer 21

modifies proteins and lipids from ER and packages them into vesicles. secretory vesicles - destined to leave the cell . lysosomes - stay in the cell.

Question 22

vesicles

Answer 22

small membrane bound sacs that have storage and transport roles in the cell. consist of a single membrane with fluid inside.

Question 23

lysosome structure

Answer 23

specialised forms of vesicles (single membrane bound sac) containing hydrolytic enzymes.

Question 24

lysosome function

Answer 24

responsible for breaking down waste material in cells including old organelles.
important immune - break down pathogens ingested by phagocytic cells.
programmed cell death or apoptosis

Question 25

cell wall function

Answer 25

Rigid layer located outside cell membrane in plant cells that provide protection, shape and support.
made out of cellulose
prevent cell bursting when placed in solution
freely permeable
defence mechanisms against invasion of pathogens

Question 26

which organelles have a double membrane?

Answer 26

nucleus , mitochondria and chloroplasts

Question 27

vacuole

Answer 27

A fluid filled sac used by cell for storage of materials. In plants there is one large fluid filled sac that provides turgor pressure

Question 28

ribosome structure

Answer 28

small organelle made of protein subunits (2)

Question 29

ribosome function

Answer 29

site of protein synthesis

Question 30

chloroplast structure

Answer 30

Double membrane organelle with thylakoids (flattened sacs) stacked together in grana which are linked by lamellae. grant contain chlorophyl pigments
contain dna and ribosomes - able to make their own protein

Question 31

chloroplast function

Answer 31

Organelles in plant cells that carry out photosynthesis. Contain chlorophyll a green pigment.

Question 32

Mitochrondria structure

Answer 32

double membrane 
inner membrane is highly folded to form cristae structure (contain enzyme used in aerobic respiration ). fluid interior is called the matrix. 
contain dna (mt)  -produce own enzymes and reproduce.

Question 33

mitochondria function

Answer 33

Supplies/converts energy to the cell in the form of ATP

site of cellular respiration