2.1 CELL STRUCTURE

Question 1

what is magnification?

Answer 1

the number of times larger an image appears, compared with the size of the object

Question 2

what is resolution?

Answer 2

the clarity of an image; the higher the resolution, the clearer the image

Question 3

what are some key feature of optical microscopes?

Answer 3

Relatively cheap and easy to use, portable and can study whole living specimens, use visible light that has a wavelength of between 400 and 700 nm

Question 4

what are some key feature of laser scanning microscopes?

Answer 4

Uses laser beams to scan something which is usually tagged with fluorescent dye
The laser causes the dye to give off light, the light is focused through a pinhole onto a detector which is connected to a computer, generating an image (3D)

Question 5

what are some key feature of Transmission electron microscopes?

Answer 5

Use electromagnets to focus a beam of electrons which is transmitted through the specimen
Denser parts absorb more electrons so they look darker
They can only be used on thin specimens which have been chemically fixed ((dehydrated and stained))
2D image produced

Question 6

what are some key feature of Scanning electron microscopes?

Answer 6

Scans a beam of electrons across the specimen
This knocks off electrons from the specimen which are gathered in a cathode ray tube to form an image, it shows the surface but they are lower resolution

Question 7

what is the maximum resolution for an optical, Transmission electron and scanning electron microscope?

Answer 7

0. 2 um
1. 0002um
2. 002 um

Question 8

what stains are used for light and electron microscopes?

Answer 8

For Light Microscopes a dye is used like methylene blue or eosin, it is taken up by some parts high contrasts the different structures (multiple stains can be used at once)
For Electron Microscopes objects are dipped in heavy metals (like lead, the metal ions scatter the electrons creating a contrast as some show up darker

Question 9

what is a cytoplasm?

Answer 9

contains a network of protein threads running through it

Question 10

what are the four functions of the cytoskeleton?

Answer 10

• The microtubules and micro filaments support the organelles keep them in position
• They help to strengthen the cell and maintain its shape
• They’re responsible for movement of materials within the cell
• The proteins of the cytoskeleton can also cause the cell to move (whole cell)

Question 11

what is the plasma membrane?

Answer 11

The membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells. It’s made of many lipids and proteins

Question 12

what is the function of the plasma membrane?

Answer 12

Regulates the movement of substances into and out of the cell. It also has receptor molecules on it, which allow it to respond to chemicals like hormones

Question 13

what is the cell wall?

Answer 13

A rigid structure that surrounds plant cells. It is made mainly of the carbohydrate cellulose

Question 14

what is the nucleus?

Answer 14

A large organelle surrounded by a nuclear envelope which contains many pores. The nucleus contains chromatin(which is made from DNA and proteins) and a structure called the nucleolus

Question 15

what if the function of the nucleus?

Answer 15

The nucleus controls the cells activities (by controlling the transcription of DNA) DNA contains instructions to make proteins. The pores allow substances to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes

Question 16

what is a lysosome?

Answer 16

A round organelle surrounded by a membrane with no clear internal structure

Question 17

what is the function of a lysosome?

Answer 17

Contains digestive enzymes. These are kept separate from the cytoplasm by the membrane and can be used to digest invading cells or to break down worn out components of the cell

Question 18

what is a ribosome?

Answer 18

A very small organelle that either floats free in the cytoplasm or is attached to the RER. It’s made up of proteins and RNA. Not surrounded by membrane

Question 19

what is the function of a ribosome?

Answer 19

The site of protein synthesis

Question 20

what is the rough ER?

Answer 20

A system of membranes enclosing a fluid- filled space. The surface is covered with ribosomes

Question 21

what is the function of the rough ER?

Answer 21

Folds and processes proteins that have been made at the ribosomes

Question 22

what is the smooth ER and what is its function?

Answer 22

Similar to rough ER, but with no ribosomes, synthesis and processes lipids

Question 23

what is a vesicle and what is it’s function?

Answer 23

A small fluid-filled sac in the cytoplasm, surrounded by membrane and it transports substances in and out of the cell and between organelles. Some are formed by the Golgi body or the ER while others are at the cell surface

Question 24

what is the golgi apparatus and its function?

Answer 24

A group of fluid-filled, membrane bound, flattened sacs. Vesicles are often seen at the edges of the sacs. It processes and packages new lipids and proteins. It also makes lysosomes

Question 25

what is a mitochondira ?

Answer 25

They’re usually oval-shaped. They have a double membrane, inner one is folded to form structures called Cristian. Inside the matrix, which contains enzymes involved in respiration

Question 26

what is the function of a mitochondria?

Answer 26

The site of aerobic respiration, where ATP is produced. They’re found in large numbers in cells that are very active and require a lot of energy

Question 27

what is a chloroplast?

Answer 27

A small flattened structure found in plant cells. Surrounded by a double membrane, also has internal membranes called thylakoids membranes which are stacked up to form grana which are linked by lamellae (Thin,flat pieces of thylakoids membrane)

Question 28

what is the function of a chloroplast?

Answer 28

Site of photosynthesis. Some parts take place in grana and other parts happen in the stromatolites (thick fluid)

Question 29

what is a centriole and its function?

Answer 29

Small hollow cylinders made of microtubules (found in animal cells but only some plant cells), involved in separation of chromosomes during cell division

Question 30

what is a cili and its function?

Answer 30

Small hair-like structures on surface membrane of animal cells, microtubules allow the cilia to move. This movement is used by the cell to move substances along the cell surface

Question 31

what is a flagellum and it’s function?

Answer 31

Flagella on Eukaryotic cells are like cilia but longer. They stick out from the surface and are surrounded by plasma membrane, microtubules contract and the flagellum move. They are used I’ve outboard motors to propel it forwards

Question 32

how are proteins made and secreted?

Answer 32

1. mRNA copy of the instructions (gene) for insulin is made in the nucleus
2. mRNA leaves the nucleus through a nuclear pore
3. mRNA attaches to a ribosome (RER), ribosome reads instructions to assemble the protein (insulin)
4. Insulin molecules are pinched off in vesicles and travel towards golgi apparatus
5. fuse with golgi apparatus
6. golgi apparatus processes and packages insulin molecules ready for release
7. packaged insulin molecules are pinched in vesicles from golgi apparatus and move toward plasma membrane
8. vesicles use with plasma membrane
9. plasma membrane opens to release insulin molecules outside

Question 33

what is an example of a prokaryote?

Answer 33

bacteria

Question 34

what is an example of a eukaryote?

Answer 34

human

Question 35

what are two differences between prokaryotes and eukaryotes?

Answer 35

P = circular DNA, extremely small, no nucleus, cell wall made of polysaccharide, few organelles, small ribosomes

E = larger cells, linear DNA, nucleus present, no cell wall, many organelles, larger ribosomes