2.1.1 Cell Structure

Question 1

what is the structure of nucleus?

Answer 1

1. nuclear envelope
   —> double membrane
2. nuclear pores
3. nucleoplasm
   —> jelly-like material
4. chromosomes
   —> protein-bound and linear dna
5. nucleolus
   —> smaller sphere inside nucleus
   —> site of rna production and makes ribosomes

Question 2

what is the function of the nucleus ?

Answer 2

1. nuclear envelope - separates content of nucleus from rest of the cell
2. pores - enable larger substances to leave the nucleus
3. nucleolus - ribosomes are made
4. chromosomes - contain organisms’s genes

Question 3

what is the structure of rough endoplasmic reticulum? (RER)

Answer 3

• system of membranes with cisternae
• coated with ribosomes

Question 4

what is the function of the RER?

Answer 4

• intraceulluar transport system
• cisternae form channels for transporting substances from one area of a cell to another

Question 5

what is the structure of smooth endoplasmic reticulum? (SER)

Answer 5

• system of membranes containing cisternae
• no ribosomes

Question 6

what is the function of SER?

Answer 6

• contain enzymes that catalyse reactions involved with lipid metabolism
• involved with synthesis and transport of lipids

Question 7

what is the function of the golgi apparatus?

Answer 7

• proteins are modified by adding carbohydrates to proteins to form glycoproteins
• proteins are packaged into vesicles

Question 8

what is the function of ribosomes?

Answer 8

• site of protein synthesis
• mRNA assembles proteins from amino acids

Question 9

what’s the function of mitochondria?

Answer 9

ATP is made during aerobic respiration

Question 10

what is the function of a lysosome?

Answer 10

• contain powerful digestive enzymes
• used to break down materials that are not needed anymore
• broken down through the process of hydrolysis

Question 11

what’s the function of cell surface membrane?

Answer 11

• controls what goes in and out of the cell
• made out of phospholipid bilayer

Question 12

what’s the function of centrioles?

Answer 12

• take part in mitosis to form spindle fibres
• only found in animals

Question 13

what is the function of a cell wall?

Answer 13

• provides high tensile strength
• insoluble
• inert

Question 14

what is the cell wall in bacteria made up of?

Answer 14

peptidoglycan

Question 15

what is the function of vacuole?

Answer 15

• membrane surrounding it is called tonoplast
• becomes turgid or flaccid altering the cell shape

Question 16

what’s a vesicle?

Answer 16

membrane bound organell which is used to transport substances

Question 17

Why do we need to stain specimens?

Answer 17

Allows specimen to become visible and to improve contrast

Question 18

what are examples of stains?

Answer 18

1. Methylene blue —> stains dna
2. Eosin —> stains cell cytoplasm

Question 19

Why are transmission microscopes used? (TEM)

Answer 19

To look at organelle detail

Question 20

Why are scanning electron microscopes used? (SEM)

Answer 20

To look at the cell surface

Question 21

What is the magnification?

Answer 21

number of times larger the image is in comparison to the object

Question 22

What is resolution?

Answer 22

Ability to distinguish between small structures that are close together

Question 23

Why does the specimen have to be thin in a light microscope?

Answer 23

So maximum light can penetrate sample

Question 24

how do you prepare a dry mount microscope slide?

Answer 24

• take a thin slice of a specimen as light needs to pass through it
• use tweezers to pick up your specimen and put it in the middle of a clean slide
• pop a cover slip on top

Question 25

how do you prepare a wet mount microscope slide?

Answer 25

- **pipette** a **small drop of water** onto the slide and **use tweezers** to **place specimen on top** of water - **tilt cover slip and lower it** onto the specimen and **try not to get air bubbles** - add a **stain**

Question 26

how do you use a light microscope?

Answer 26

1. put **slide** you want to look at **on the stage** 2. select **lowest powered objective lens** 3. use **coarse adjustment knob** to **bring stage up** to below the **objective lens** 4. look down the **eyepiece lens** and use coarse adjustment knob to move stage until image is in focus 5. **adjust focus** with **fine adjustment knob** 6. **switch** to **higher powered objective lens** if needed

Question 27

what is the role of the cytoskeleton within the cell?

Answer 27

- whole **cell support** - **movement** of **cilia and flagella** - changing **cell shape** - **movement of organelles** and **chromosomes**

Question 28

what are the main components of the cytoskeleton?

Answer 28

1. microfilaments 2. microtubules 3. intermediate filaments

Question 29

what do all the components in the cytoskeleton require?

Answer 29

ATP

Question 30

what are cell walls in a prokaryote made of?

Answer 30

- **peptidoglycan** - it has **high tensile strength**

Question 31

what are prokaryotes made of?

Answer 31

rRNA and protein

Question 32

what’s found in both prokaryotes and eukaryotes?

Answer 32

ribosomes

Question 33

do root cells contain chloroplasts?

Answer 33

no

Question 34

how do you correctly add a stain?

Answer 34

- place **stain at edge of sample** - **lower cover slip** at an **angle** - use **more than one stain** - use **blotting paper** to **remove excess stain**

Question 35

what is the role of the membrane in the RER?

Answer 35

- **holds ribosomes** in place - **separates proteins** from **cytoplasm**

Question 36

why do goblet cells have mitochondria?

Answer 36

to produce **a lot of ATP**

Question 37

do yeast cells have nucleus?

Answer 37

yes

Question 38

what’s the means of cell division in a yeast cell?

Answer 38

budding

Question 39

what are some structural similarities between mitochondria and prokaryotes?

Answer 39

- both have **70s ribosomes** - both have **circular DNA**

Question 40

how are molecules secreted after translation?

Answer 40

- **transport vesicle** from RER - **modified at golgi** - **packaged** into **secretory vesicle** - vesicle **moves along cytoskeleton** - vesicle **fuses with cell surface membrane** - secretion happens by **exocytosis**

Question 41

how can vesicles be moved around the cell?

Answer 41

- **attaches** to **cytoskeleton** - moves by **change in length of microtubules**

Question 42

how would you measure something under a microscope?

Answer 42

- use **eyepiece graticule** - measure in **epu** - take **repeat measurements** and calculate a **mean**