Nucleus, ER, Ribosomes and Golgi body

Question 1

Ultrastructure

Answer 1

The detailed structure revealed by the electron microscope.

Question 2

A nucleus is the…

Answer 2

largest organelle.

Question 3

A nucleus is surrounded by…

Answer 3

two membranes called the nuclear envelope.

Question 4

The outer membrane of the nuclear envelope is…

Answer 4

continuous with the endoplasmic reticulum.

Question 5

The nuclear envelope has many small…

Answer 5

pores called nuclear pores. This allows and controls exchange between the nucleus and the cytoplasm.

Question 6

Examples of substances leaving the nucleus:

Answer 6

mRNA and ribosomes for protein synthesis.

Question 7

Examples of substances entering the nucleus:

Answer 7

proteins to help make ribosomes, nucleotides, ATP and hormones such as thyroid hormones T3

Question 8

ATP stands for…

Answer 8

adenosine triphosphate.

Question 9

Chromatin

Answer 9

The chromosomes are in a loosely coiled state known as chromatin(except nuclear division)

Question 10

Chromosomes contain…

Answer 10

DNA which is organised into functional units called genes.

Question 11

Genes control the…

Answer 11

activities of the cell and inheritance, so the nucleus controls the cell’s activities.

Question 12

Nucleolus makes…

Answer 12

ribosomes, using information in its own DNA.

Question 13

Endoplasmic Reticulum (ER)

Answer 13

Is an extensive system of membranes running through the cytoplasm.

Question 14

(ER)The membranes form…

Answer 14

an extensive system of flattened compartments called sacs, spreading through the cell.

Question 15

(ER) The sacs can be…

Answer 15

interconnected to form a complete system (reticulum). The ER is continuous with the outer membrane of the nuclear envelope.

Question 16

Rough ER

Answer 16

It is covered with many ribosomes. Visible as black dots.

Question 17

Ribosomes consist…

Answer 17

of two subunits. A large and small subunit.

Question 18

On the rough ER, the ribosomes are…

Answer 18

small only about 25nm in diameter. Made of RNA (ribonucleic acid) and protein.

Question 19

Proteins made by the ribosomes on the rough ER…

Answer 19

enter the sacs and move through them. The proteins are often modified on the journey.

Question 20

Small sacs called…

Answer 20

vesicles, which can break off from the ER and these can join together to form the Golgi body.

Question 21

The Golgi body forms a part of…

Answer 21

the secretory pathway, as the proteins can be exported from the cell via the Golgi body.

Question 22

Smooth ER

Answer 22

It lacks ribosomes and has a completely different function.

Question 23

A function of smooth ER

Answer 23

It makes lipids and steroids such as cholesterol and the reproductive hormones oestrogen and testosterone.

Question 24

Golgi body is…

Answer 24

a stack of flattened sacs.

Question 25

More than one Golgi body can…

Answer 25

be present in the cell.

Question 26

(Golgi body) The stack is constantly…

Answer 26

being formed at one end of the vesicles which bud off from the ER and broken down again at the other end to from Golgi vesicle.

Question 27

The stack of sacks together with…

Answer 27

associated vesicles is referred to as the Golgi body.

Question 28

The Golgi body collects…

Answer 28

processes and sorts molecules (mainly proteins form rough ER), ready for transport in Golgi vesicle either to other parts of the cell or out of the cell-secretion.

Question 29

(glycoprotein)Example of protein processing in Golgi body is…

Answer 29

the addition of sugars to proteins to make molecules of glycoproteins.

Question 30

(functioning protein)Example of protein processing in Golgi body is…

Answer 30

the removal of the first amino acid, methionine, from newly formed proteins to make a functioning protein.

Question 31

In plants, enzymes in Golgi body…

Answer 31

concert sugars into cell wall components.

Question 32

Golgi vesicles are also used to make…

Answer 32

lysosomes.