Cell Structure

Question 1

Structure of a nucleus

Answer 1

Contains DNA which controls activity of cells

contains chromatic which is DNA wound with histone proteins

Question 2

What is the nucleolus?

Answer 2

region in the nucleus where ribosomes are made

Question 3

What is the nuclear envelope

Answer 3

Double membrane which surrounds the nucleus.

Contains pores which allow small molecules to pass into cytoplasm

Question 4

What is the RER?

Answer 4

attached to the nuclear envelope and is covered with ribosomes

Site of protein synthesis

Question 5

What is the SER

Answer 5

Synthesises lipids
e.g cholesterol/steroid hormones

Question 6

What is the golgi apparatus

Answer 6

group of fluid filled, flattened double membranes called cisternae

It receives, modifies, processes and packages proteins and lipids and transports them in vesicles

Site of vesicle synthesis

Question 7

What are ribosomes?

Answer 7

translates RNA into proteins

either float freely in cytoplasm or on the RER

Made of one large subunit and one small subunit

20nm

Question 8

What are mitochondria?

Answer 8

Double membrane with folds called cristae surrounded by mitochondrial matrix

Site of ATP production during aerobic respiration.

Self replication

2-5 um

Question 9

What are lysosomes?

Answer 9

single membraned sacs

contain digestive enzymes which breakdown organelles and foreign material
0.1-0.5 um

Question 10

What are chloroplasts?

Answer 10

Site of photosynthesis

double membrane that has internal thylakoid membranes arranged in stacks to form grana linked by lamellae

6-10 um

Question 11

what is the plasma membrane?

Answer 11

consists of phospholipid bilayer with added proteins as carriers.

Contains choleterol to regulate membrane fluidity

Controls movement of substances in and out of cell

Question 12

What are centrioles?

Answer 12

Bundles of microtubules which form splindle fibre during mitosis

Important for formation of cilia and flagella

Question 13

what is the cell wall?

Answer 13

A rigid structure that provides support to the cell

Cellulose in plants

Chitin in fungi

murein in prokaryotes

Question 14

what is a flagella?

Answer 14

tail-like structure made of bundles of microtubules

Microtubules contract to move cell

Question 15

what are cilia?

Answer 15

found on surface of some cells

contain bundles of microtubules which contract to move cillia

found on epithelial cells in trachea to waft mucus up

Question 16

what is a vacuole?

Answer 16

organelle which stores cell sap, nutrients and proteins

keeps plants turgid

Question 17

how are proteins produced?

Answer 17

mRNA is translated into a polypeptide chain in the ribosomes

polypeptide chain is folded in RER and transported to golgi apparatus via a vesicle

At the golgi, they are modified and processed.

The protein is packaged into a vesicle and is transported to the plasma membrane

Vesicle will fuse with plasma membrane and release proteins by exocytosis

Question 18

What is the cytoskeleton?

Answer 18

Network of protein threads that run through the cytoplasm.

Protein threads are microfilaments and microtubules

Supports the cells organells and keeps them in position

maintains its shape

movement of cilia and flagella

Question 19

What are pili?

Answer 19

Hair like structures which stick out of plasma membrane

Used for cell communication

Question 20

What is the mesosome?

in bacteria

Answer 20

folded part of the inner membrane

involved in chemical reactions

Question 21

What are plasmids?

Answer 21

small, circular rings of DNA in the cytoplasm

replicate independently

Question 22

what is the slime capsule?

Answer 22

protect the bacterium against immune system attacks