Cells and Organelles

Question 1

Cytoplasm

Answer 1

• The contents of a cell, excluding the nucleus.

Function: thick fluid within the cell membrane that suspends all the structures within it.

Structure: Liquid made up of cytosol (75-90% water and dissolved substances e.g. salts and carbohydrates).

Question 2

Centrioles

Answer 2

• Each of a pair of minute cylindrical organelles near the nucleus in animal cells, involved in the development of spindle fibres in cell division.

Function: a pair of cylindrical structures located near the nucleus.

Structure: involved in the reproduction of the cell.

Question 3

Smooth Endoplasmic Reticulum

Answer 3

• A form of endoplasmic reticulum that is involved in the synthesis of lipids, not covered in ribosomes.

Function: provide a surface for chemical reactions, while the channels are for storing or transporting molecules.

Structure: no ribosomes attached to the outside.

Question 4

Rough Endoplasmic Reticulum

Answer 4

• A form of endoplasmic reticulum that is covered with ribosomes involved in the synthesis of proteins.

Function: provide a surface for chemical reactions, while the channels are for storing or transporting molecules.

Structure: ribosomes are attached to the outside of some membranes.

Question 5

Ribosomes

Answer 5

• Site of protein synthesis; located on the surface of rough endoplasmic reticulum

Function: Amino acids are joined together at the ribosomes to make proteins.

Structure: very small and spherical. They may be free in the cytoplasm but most are attached to the membranes.

Question 6

Cytoskeleton

Answer 6

• An internal scaffolding of protein fibres within the cytoplasm of a cell.

Function: give the cell its shape and assist in the movement of materials, organelles or the whole cell.

Structure: consists of microfilaments and microtubules.

Question 7

Inclusions

Answer 7

• Chemical substances inside a cell in the form of granules or droplets.

Substances that are not part of the cell structure but are found in the cytoplasm.

Example: haemoglobin in red blood cells; pigments in cells of the skin.

Question 8

Lysosomes

Answer 8

• A small sphere formed from a Golgi body; contains digestive enzymes

Function: break down materials that are taken into the cell or break down worn-out organelles.

Structure: small spheres that contain enzymes.

Question 9

Nucleus

Answer 9

• A large organelle in a cell containing DNA

Function: contains DNA (genetic material that determines the type of proteins a cell can make) and plays a part in manufacturing proteins.

Structure: largest organelle in the cell and is usually oval or spherical in shape.

Question 10

Nucleolus

Answer 10

• A structure within a nucleus; involved in protein synthesis.

Function: plays a part in manufacturing proteins.

Structure: small spherical shape organelle inside the nucleus.

Question 11

Mitochondria

Answer 11

• A structure in the cytoplasm of a cell in which the aerobic stage of respiration occurs.

Function: release energy for the cell through the process of respiration.

Structure: spherical or elongated structure with a double membrane.

Question 12

Golgi body

Answer 12

• A structure in the cytoplasm of a cell consisting of a stack of flattened channels; it packages materials for secretion from the cell.

Function: modify proteins and package them in vesicles for secretion from the cell.

Structure: flattened, membranous bags stacked on top of each other.

Question 13

Cell Membrane

Answer 13

• A membrane that forms the external boundary of a cell

Function: separates the inside of the cell from outside and controls which substances get into or out of the cell.

Structure: the outer boundary of the cell, made up of a double membrane of lipid molecules and associated proteins.

Question 14

Vesicle

Answer 14

• A small membrane-bound cavity in the cytoplasm of a cell, smaller than a vacuole.

Function: transports materials into, out of or within the cell.

Structure: a membrane-bound sac