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Flashcards in Cell Biology Deck (68):
1

What's another name for plant and animal cells?

Eukaryotic cells

2

What's another name for bacterial cells?

Prokaryotic cells

3

What do plant cells have?

Nucleus, cell membrane, cell wall, cytoplasm, chloroplasts and a vacuole

4

What do animal cells have?

Nucleus, cell membrane, cytoplasm, mitochondria and ribosomes

5

What do bacterial cells have?

A lot smaller in comparison. Cytoplasm and a cell membrane surrounded by a cell wall. Genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids

6

Function of nucleus

Controls the activities of the cell and contains genetic material

7

Function in cytoplasm

Where most chemical reactions take place. Contains enzymes that control these chemical reactions

8

Function of cell membrane

Controls the passage of substances into and out of the cell

9

Functions of mitochondria

Where aerobic respiration takes place. Respiration transfers energy that the cell needs to work

10

Function of ribosomes

Where proteins are made in the cell

11

Function of chloroplasts

Absorb light to make food by photosynthesis. They contain chlorophyll which absorbs the light needed for photosynthesis

12

Function of vacuole

Filled with cell sap

13

Function of cell wall

Made of cellulose, which strengthens the cell

14

What is a specialised cell?

A cell that has become differentiated to carry out a particular function

15

Name some specialised animal cells

Sperm cells, nerve cells and muscle cells

16

Name some specialised plant cells

Root hair cells, xylem and phloem cells

17

Light microscopes

Uses light and lenses to form an image of a specimen and magnify is. Let us see individual cells and large subcellular structures like nuclei

18

Electron microscopes

Used electrons instead of light to form an image. They have much higher magnification than light microscopes. Let us see even tinier things like ribosomes

19

How to calculate magnification

Magnification = image size
-----------
Real size

20

μm into mm

Divide by 1000. 5000 μm divided by 1000 = 5mm

21

Write 0.0025 in standard form

-the first number needs to be between 1 and 10 so the decimal point needs to move after the 2
-count how many places the dp has moved, this is the power of 10.
= 2.5 x 10^-3

22

What is resolution

Is the ability to distinguish between two points, so a higher resolution gives a sharper image

23

How to prepare a slide to view onion cells

1) add a drop of water into the middle of a clean slide
2) cut up an onion and separate it out into layers. Use tweezers to peel off some epidermal tissue from the bottom of one of the layers.
3) place the epidermal tissue into the water on the slide
4) add a drop of iodine solution , this highlights objects in a cell.
5) place a cover slip on top without trapping any air bubbles

24

How to use a light microscope

1) clip the slide into the stage and select the lowest-powered objective lens
2) use the coarse adjustment knob to move the stage up to just below the objective lens
3) look down the eye piece and use the coarse adjustment knob to move the stage downwards until the image is in rough focus
4) adjust the focus with the fine adjustment knob until a clear image of the cells is visible

25

Sperm cells

Reproduction
Function is to get the male DNA to the female DNA.
It has a long tail and a streamlines head to help it swim to the egg.
Lot of mitochondria in the cell to provide the energy needed.
Also carries enzymes in its head to digest through the egg cell membrane

26

Nerve cells

Rapid signalling
Function is to carry electrical signals from one part of the body to another.
These cells are long and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.

27

Muscle cells

Contraction
Function is to contract quickly.
These cells are long and contain lots of mitochondria to generate the energy needed for contraction

28

Root hair cell

Absorbing water and minerals
Root hair cells are on the surface of plant roots which grow into long "hairs" that stick out into the soil.
This gives the plant a big surface area for absorbing water and mineral ions from the soil

29

Phloem and xylem cells

Transporting substances
For phloem and xylem tubes which transport substances such as food and water around plants.
To form tubes 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 through them

30

What is cell differentiation

It's the process by which a cell changes to become specialised for its job

31

Info about cell differentiation

As an organism develops, cells differentiate to form different types of cells.
Most types of animal cell differentiate at an early stage whereas many types of plant cells retain the ability to differentiate throughout life.
As a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a specialised cell

32

What is a stem cell

An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation

33

Function of stem cells in embryos

They can be cloned and made to differentiate into most different types of human cells

34

Function of stem cells in adult animals

Stem cells from adult mine marrow can form many types of cells including blood cells

35

Function of stem cells in the meristems in plants

Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant

36

Adult stem cells for medicine

Used to cure diseases. For example stem cells transferred from bone marrow of a healthy person can replace faulty blood cells in the patient who receives them

37

Embryonic stem cells for medicine

Can be used to replace faulty cells in sick people- you could make insulin-producing cells for people with diabetes, never cells for people paralysed by spinal injuries.

38

What's therapeutic cloning

A type of cloning where an embryo could be made to have the same genetic information as the patient, so the stem cells produced wouldn't be rejected by the patient's body if used to replace faulty cells

39

What's the risk involved in using stem cells in medicine

Stem cells grown in the lab may become contaminated with a virus which could be passed on to the patient and so make them sicker

40

Why are some people against stem cell research?

-human embryos shouldn't be used for experiments since each one is a potential human life

41

Why are some people for stem cell research

-curing patients who already exist and who are suffering is more important than the rights of embryos
-embryos used in the research are usually unwanted ones from fertility clinics which would probably would of just been destroyed.

42

Stem cells in plants in meristems

Used to produce clones of plants quickly and economically.
Rare species can be cloned to protect from extinction.
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers

43

Chromosomes

The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes.

44

Pairs of chromosomes

Body cells normally have two copies of each chromosome- one from the organism's 'mother' and one from its 'father'.

45

Mitosis

Body cells in multicellular organisms divide to produce new cells as part of stages called the cell cycle
Multicellular organisms use mitosis to grow or replace cells that have been damaged.

46

What are the two main stages of the cell cycle

Growth and DNA replica
Mitosis

47

Growth and DNA replication

In a cell that's not dividing, the DNA is all spread out in long strings.
Before it divides, the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
It then duplicates its DNA- so there's one copy for each new cell.

48

Growth and DNA replication

In a cell that's not dividing, the DNA is all spread out in long strings

49

Once the cells contents and DNA have been copied, the cell is ready for mitosis

The chromosomes line up at the centre of the cell and cell fibres pull them apart. Two arms of each chromosome go to opposite ends of the cell.
Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells.
Lastly the cytoplasm and cell membrane divide.
The cell has now produced two new identical daughter cells.

50

What is diffusion

The spreading out of particles from an area of higher concentration to an area of lower concentration.
Substances may move into and out of cells across the cell membranes via diffusion

51

What does diffusion happen in

Both solutions and gases as the particles are free to move about randomly

52

What factors affect the are of diffusion

The difference in concentrations (concentration gradient)- the bigger the difference the faster the diffusion rate.
The temperature- the higher the faster as the particles have more energy so move faster.
The surface area of the membrane- the larger the faster

53

What's a partially permeable membrane

A membrane with small holes to let tiny molecules pass through

54

Give examples of substances transported in and out of cells by diffusion

Oxygen and carbon dioxide for gas exchange
Waste product urea from cells into the blood plasma for excretion in the kidney

55

What is osmosis

The movement of water molecules across a partially permeable membrane from a region of higher water concentration to one of lower concentration. Water in lower concentrated solution goes into higher

56

Potato experiment

Distilled water- potato grows as there is less water in potato so the higher concentration of water goes into the lower concentration
Salt solutions- potato shrinks as water ALWAYS moves into the more concentrated solution

57

How to work out the percentage change in mass

Initial mass- 3.5
Final mass- 3.9
Change in mass- 0.4
0.4
---
3.5

58

active transport

Moves substances from a more dilute solution to a concentrated solution (against the concentration gradient). This requires energy from respiration

59

Active transport in root hair cells

Plants need mineral ions for healthy growth.
The concentration of minerals is usually higher in the root hair cells than in the soil around them. So the root hair cells can't use diffusion to take up minerals from the soil

60

Active transport in the gut

It allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has higher sugar concentration.

61

Surface area to volume ratio

4x4x2

62

Single called organism

Has a relatively large surface area to volume ratio

63

Multi cellular organisms

Have a smaller surface area to volume ratio

64

Why do multicellular organisms need exchange surfaces

They have a small surface area to volume ratio so not enough substances can diffuse from their outside surface to supply their entire volume.

65

Diffusion in small intestine

Inside of small intestine is thin with a large surface area, allowing absorption to happen quickly. To get a big surface area the inside wall is lined with villi

66

Diffusion in lungs

They have a huge surface area and moist lining for dissolving gases

67

Diffusion in gills

Have large surface area for gas exchange

68

Diffusion in leaves

Gases diffuse in and out of cells