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Flashcards in Cell Biology Deck (76):
1

What is a prokaryotic cells characteristics?

Small and simple

2

What is a eukaryotic cells characteristics?

Complex (bigger than prokaryotic cells)

Include all animal and plant cells

3

Eukaryotes are...

...organisms that are made up of eukaryotic cells

4

A prokaryote is...

...a prokaryotic cell - it is a single-celled organism.

5

What does an animal cell contain?

Nucleus,
Mitochondria,
Cytoplasm,
Cell membrane,
Ribosomes

6

What does a plant cell contain?

Nucleus
Mitochondria
Cytoplasm
Cell membrane
Ribosomes
Cell wall
Chloroplasts
Permanent vacuole

7

What is the purpose of the nucleus?

It contains genetic material that controls the activities of the cell

8

What is the purpose of mitochondria?

These are where the most of the reactions for AEROBIC respiration take place.

Respiration transfers energy that the cell needs to work

9

What is the purpose of cytoplasm?

It is a gel-like substance where most of the chemical reactions happen.

It contains enzymes that control these chemical reactions

10

What is the purpose of the cell membrane?

It holds the cell together and controls what goes in and out

11

What is the purpose of ribosomes?

These are where the proteins are made in the cell

12

What is the purpose of the (rigid) cell wall?

It is made of cellulose.
It supports the cell and strengthens it together

13

What is the purpose of chloroplasts?

These are where photosynthesis occurs, which makes food for the plant.

They contain a green substance called chlorophyll which absorbs the light needed for photosynthesis

14

What is the purpose of the permanent vacuole?

It contains cell sap, a weak solution of sugar and salts

15

List the features of a bacteria cell

They are prokaryotes
They don't have a 'true' nucleus - they have a single circular strand of DNA that floats freely in the cytoplasm
They can contain one or more small rings of DNA called plasmids
They don't have chloroplasts or mitochondria

16

What does a bacteria cell contain?

Cell membrane
Cell wall
Cytoplasm
Circular strand of DNA
plasmid

17

Microscopes let us...

See things that we can't see with the naked eye

18

Light microscopes use ...

...light and lenses to form an image of a specimen and magnify it

They let us see individual cells and large sub cellular structures

19

Electron microscopes use...

...electrons to form an image.

They have a much higher magnification and resolution than light microscopes.

They let us see much smaller things in more detail.

20

What is the formula for magnification?

Magnification = image size / real size

/ = divided by

21

How do you prepare a slide to view onion cells?

1) add a drop of water to the middle of a clean slide
2) cut up and onion and separate it out into layers. Use tweezers to peel of some epidermal tissue from the bottom of one of the layers
3) using the tweezers l, place the epidermal tissue into the water on the slide
4) add a drop of iodine solution
5) place a cover slip on top.

22

What are the parts of a LIGHT microscope?

Eyepiece
Coarse adjustment knob
Fine adjustment knob
Light
Stage
High and low power objective lenses

23

What is differentiation?

Differentiation is the process by which a cell changes to become specialised for its job

24

Why do cells differentiate?

To become specialised

25

As cells change, they develop ...

(Differentiation + Specialisation)

...different sub cellular structures and turn into different types of cells. This allows them to carry out specific functions

26

Most differentiation occurs as an organism ...

...Develops

27

When do animals loose the ability to differentiate?

At an early stage, after they have become specialised.

28

When do plant cells loose the ability to differentiate

Most plants cells don't ever lose this ability

29

What are cells that differentiate in mature animals mainly used for?

Repairing and replacing cells, such as skin or blood cells.

30

What are undifferentiated cells called?

Stem cells

31

Give 5 examples of specialised cells

Sperm cells
Nerve cells
Muscle cells
Root hair cells
Phloem and Xylem cells

32

What are sperm cells specialised for?

What information can be given about sperm cells?

Reproduction.

-The function of a special is to get the male DNA to the female DNA
-It has a long tail and a streamlined head to help it swim to the egg.
-There are a lot of mitochondria in the cell to provide the energy needed.
-It carries enzymes in its head to digest through the egg cell membrane

33

What are nerve cells specialised for?

What information can be given about nerve cells?

Rapid signalling

-The function of the nerve cell is to carry electrical signals from one lady of the body to another
-These cells are long (to cover more distance) and have branches connections at their ends to connect to the other nerve cells and form a network throughout the body

34

What are muscle cells specialised for?

What information can be given about muscle cells?

Contraction

-The function of a muscle cell is to contract quickly
-These cells are long (so that they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction

35

What are root hair cells specialised for?

What information can be given about root hair cells?

Absorbing water and minerals

-Root hair cells are Ella in the surface of plant roots, which grow into long "hairs" that stuck out into the soil
-This gives the plant a big surface area for absorbing water and mineral ions from the soil

36

What are phloem and xylem cells specialised for?

What information can be given about phloem and xylem cells?

Transporting substances

-Phloem and xylem cells form phloem and xylem tubes, which transport substances such as food and water around plants
-To form the tube, the cells are long and joined end to end
-Xylem cells are hollow in the centre and phloem cells have very few subcellular structures so that stuff can flow trough them

37

Embryonic stem cells can turn into...

...ANY type of cell

38

What can undifferentiated cross (stem cells) do?

They can divide to produce lots more undifferentiated cells.

They can differentiate into different types of cell, depending on what instructions they're given.

39

Where are stem cells found?

In early human embryos

40

Where are adult stem cells found?

In certain places like bone marrow

41

What can adult stem cells turn into?

Only certain ones such as blood cells

42

How can stem cells be used in medicine?

Adult stem cells are already used to cure disease e.g stem cells transferred from bone marrow from a healthy person can replace faulty blood cells in the receiver.

Embryonic stem cells could also be used to replace faulty cells in sick people e.g you could make insulin-producing cells for people with diabetes.

43

Why are some people against stem cell research?

They feel that human embryos shouldn't be sued for experiments since each one is potential human life HOWEVER others think that curing patients who already exist and who are suffering is more important than the rights of embryos

44

How do stem cells produce identical plants?

1) stem cells are found in the meristems of plants
2) throughout the plants life cells in the meristem tissues can differentiate into any type of plant cell
3) these stem cells can be used to produce clones of whole plants quickly and cheaply
4) they can be used to grow more plants of rare species
5) stem cells can also be used to grow crops of identical plants that have desired features for farmers

45

What do chromosomes contain?

Genetic information

46

What are chromosomes?

Coiled up lengths of DNA molecules

47

How many pairs of chromosomes does a human cell have?

23

48

How many copies of each chromosomes do body cells normally have?

2, one from the organisms mother and one from its father

49

What is stage of the cell cycle called when the cell divides?

Mitosis

50

Why do body cells in multicellular organisms divide?

To produce new cells as part of a series of stages called the cell cycle

51

What do multicellular organisms uses mitosis for?

They use mitosis to grow or replace cells that have been damaged

52

What is the result at the end of the cell cycle?

Two new cells identical to the original cell with the same number of chromosomes

53

What are the two main stages of the cell cycle?

Growth and DNA replication

Mitosis

54

What are the stages of growth and DNA replication in the cell cycle?

Before mitosis, the cell has to grow and increase the amount of subcellular structures (such as mitochondria and ribosomes)

It then duplicates its DNA

55

What are the stars of mitosis in the cell cycle?

The chromosome line up at the centre of the cell and cell fibres pull them apart. the two arms of each chromosome go to opposite ends of the cell.

Membranes form around each of the sets. These become the nuclei of the two new cells.

Lastly, the cytoplasm and cell membrane divide

56

What happens in binary fission?

The cell splits into two

57

What are the stages of binary fission?

1) the circular NDA and plasmids replicate
2) the cells get bigger and the circular DNA strands moves to the opposite 'poles' (ends) of the cell.
3) the cytoplasm begins to divide and new cell walls begin to form
4) the cytoplasm dives and two daughter cells are produced

58

What is diffusion?

Diffusion is the movement of particles form and area do higher concentration to an area of lower concentration

59

Where does diffusion occur and why?

In solutions and gasses because the particles are free to move about randomly

60

How can you increase the rate of diffusion?

Having a higher temperature

Having a bigger concentration gradient

61

What do cell membranes do?

They hold the cell together but they let stuff in and out as well - only very small molecules can diffuse through cell membranes e.g oxygen

62

The is the rate of diffusion faster with a larger surface area of the membrane

Because mor else tickets can pass through at once

63

What Is osmosis?

Osmosis is the movement of water molecules across a semi/partially permeable membrane from an area of high concentration to an area of low concentration

64

What is active transport?

The movement of molecules from an area of low concentration to an area of high concentration.

In active transport, molecules move against the concentration gradient no therefore require an input of energy from the cell

65

Give an example of active transport being used in a plant?

Root hair cells take in minerals using active transport

66

Give an example of active transport in human body's

Active transport stops us from starving.

Active transport is used in the gut when there is a lower concentration of nutrients from the gut but a higher concentration of nutrients in the blood

67

Give an example of how cells can use diffusion to take in substances they need and get rid of waste products

- Oxygen and carbon dioxide are transferred between cells and the environment during gas exchange

- In humans, urea diffuses from cells into the blood plasma for removal from the body by the kidneys

68

What's the difference between single-called
Organisms and multicellular organisms when exchanging substances

I'm single-celled organisms, gases and dissolved substances can diffuse directly into the cell across the cell membrane because they have a large surface area compared to their volume, so enough substances can be exchanged across the membrane to supply the volume of the cell.

HOWEVER

Multicellular organisms have a smaller surface area compared to their volume, so not enough substances can diffuse to supply their volume.

Multicellular organisms need an exchange surface for efficient diffusion

69

Exchange surfaces are adapted to maximise effectiveness.

What do they contain and why?

They have a thin membrane (shorter distance)
They have a large surface area (faster rate of diffusion)
In animals they have lots of blood vessels (to get stuff in and out of the blood quickly)
Gas exchange surfaces in animals are often ventilated

70

What is the job of the lungs?

To transfer oxygen to the blood and to remove waste carbon dioxide from it.

71

Where does gas exchange happen in the lungs?

In little air sacs called alveoli

72

How are the alveoli specialised to maximise the diffusion of oxygen and CO2?

They have:
-An enormous surface area
-A moist lining for dissolving gases
-Very thin walls
-A good blood supply

73

Where are villi found in the body?

Inside of the small intestine

74

What do the villi do?

They increase the surface area so that digested food is absorbed quicker into the blood

75

What do villi have?

A single layer of surface cells
A very good blood supply to assist quick absorption

76

How's does CO2 enter the leaf and how does oxygen and water vapour escape?

-CO2 diffuses in through the stomata
-Oxygen and water vapour diffuse out through the stomata