organelle structures and functions

Question 1

cytoplasm/cytosol

Answer 1

the cytoplasm is a thick fluid within the cell membrane with all the structures suspended in it. It contains the cytosol and the organelles. The cytosol is the water component of the cytoplasm which is 70-90% water and other dissolved substances

• Site of metabolic reactions (site of anaerobic respiration)
• fills space between nuclear membrane and cellular membrane
• controlling osmotic pressure of the cell and the flow of chemicals into and out of cell

Question 2

cell membrane

Answer 2

outer boundary of the cell consisting of a phospholipid bilayer and associated proteins

• surround and protects
• supports cell and surrounding tissue
• sensitive to changes
• controls the passage of materials in and out of the cell

Question 3

organelles

Answer 3

specialised structures suspended in the cytosol and carry out particular functions

Question 4

nucleus

Answer 4

the nucleus is ovoid or spherical in shape and contains genetic material which controls and regulates the activities of the cell (usually in the form of chromatin) which is suspended in the nucleoplasm. It also contains a nucleolus which contains rna and is the site of production of ribosomes which are used for further protein synthesis. The nucleoplasm is separated from the cytoplasm by a double-layered nuclear membrane which has pores to allow the passage of materials in and out of the nucleus.

• contains genetic material and storage of hereditary information
• production of ribosomes
• controls and regulates the activities of the cell
• pores allow the passage of large molecules
• nuclear membrane separates the nucleoplasm from the cytoplasm

Question 5

endoplasmic reticulum (smooth/rough)

Answer 5

pairs of parallel membranes that connect the cellular membrane to the nuclear membrane. Smooth has nothing attached while rough has ribosomes attached to the surface.

• surface for which chemical reactions can occur
• the channels are used for transport and storage of materials (such as proteins)

Question 6

ribosomes

Answer 6

spherical, small and numerous proteins found suspended in the cytoplasm or connected to the endoplasmic reticulum.

• production of proteins from RNA (amino acids join to make proteins)

Question 7

mitochondrion

Answer 7

spherical/overical structures suspended in the cytoplasm. Site of areobic respiration which produces energy. Have a double membrane, an outer membrane that is smooth and surrounds the structure, and an inner membrane that is folded known as the cristae. The space between the inner membrane is known as the matrix. large surface area due to folding of cristae

Question 8

Golgi apparatus and vesicles

Answer 8

series of flattened membranes stacked upon one another that function to package and prepare proteins for their secretion from the cells. These proteins are packaged in vesicles which are membrane-bound sacs which pinch off from the Golgi apparatus.

Question 9

lysosomes

Answer 9

spheres that contain enzymes that are able to break down lipids, carbohydrates, proteins and nucleic acids. Also able to break down worn-out organelles. Formed in Golgi apparatus

Question 10

centrioles

Answer 10

pair of cylindrical structures located near nucleus and responsible for reproduction of the cell

Question 11

cilia and flagella

Answer 11

cilia: small and numerous projections from the outside of the cell membrane which can beat back and forth to move the cell or materials on top of the cell.

Flagella: 1 or 2 elongated projections from the outside of the cell membrane used to propel the cell. Prominent in bacteria, seen in sperm which are the only human cell with this structure.

Question 12

Cytoskeleton

Answer 12

a framework of protein fibres consisting of microfilaments and microtubules.
Microfilaments: move cells or materials in the cell
microtubules: hollow tubes which keep organelles in place or move them around.