A2.2 Cell Structure

Question 1

cell theory

Answer 1

Cells are the basic structural unit of all living organisms
cells can only arise from pre existing cells
smallest units of life

Question 2

unicellular

Answer 2

consisting of a single cell

Question 3

protists

Answer 3

eukaryotes consisting of single celled organisms
NOT plant animal or fungi

Question 4

features common in all cells

NOT STRUCTURES

Answer 4

• Are surrounded by a membrane
• Contain genetic material
• Have chemical reactions occurring within the cell that are catalysed by enzymes

Question 5

How do optical microscopes work

Answer 5

Light is directed through the thin layer of biological material that is supported on a glass slide
This light is focused through several lenses so that an image is visible through the eyepiece

Question 6

optical microscopes

Answer 6

light

Question 7

optical microscopes advantages

Answer 7

easy to use
cheaper
can observe dead or living in colour
cell movement can be studied
quick preparation

Question 8

optical microscopes disadvantages

Answer 8

max magnification of 1500x
low resolving power

Question 9

components of an optical (light) microscope are

Answer 9

The eyepiece lens
The objective lenses
The stage
The light source
The coarse and fine focus

Question 10

graticule

Answer 10

small disc that has an engraved scale. It can be placed into the eyepiece of a microscope to act as a ruler in the field of view

Question 11

calibrated

Answer 11

This is done by using a scale engraved on a microscope slide

By using the two scales together, the number of micrometers each graticule unit is worth can be worked out

Question 12

Magnification general formula

Answer 12

magnification = image / real

Question 13

electron microscope

Answer 13

in which a beam of electrons replaces light so the powers of magnification and resolution are corresponding much greater

Question 14

advantages of electron microscope

Answer 14

magnification of 100000 x to 300000 x

Question 15

disadvantages of electron microscope

Answer 15

expensive
cells have to be killed
no movement
has to be stained or dyed
preparation takes days

Question 16

1 m in mm

Answer 16

1000 mm

Question 17

1mm in um

Answer 17

1000 um

Question 18

1 um in nm

Answer 18

1000 nm

Question 19

1 cm in um

Answer 19

10000 um

Question 20

resolution

Answer 20

amount of detail that can be seen

Question 21

scale bar

Answer 21

straight line on the drawing or micrograph that represents the actual size before the image was enlarged

Question 22

Qualitative data

Answer 22

non-numerical data such as colour and presence of structures which can also be determined using microscopes

Question 23

quantitative observations

Answer 23

collection of data which are focused on numbers and values such as measurements of length, height, volume, or values of quantity and frequency

Question 24

staining

Answer 24

chemicals that bind to structures within the sample and are used to make them show more clearly when viewed under microscope

Question 25

iodine staining

Answer 25

starch - blue black

Question 26

methylene blue

Answer 26

cell nuclei and DNA - stain blue

Question 27

gram stain

Answer 27

divides nucleus into gram positive and negative Gram-positive organisms - purple or blue gram-negative organisms - pink or red

Question 28

DNA

Answer 28

- The presence of DNA means that a new cell can be formed from an old cell, as genetic material is able to be stored and transferred - DNA also controls the production of enzymes and other vital proteins within the cell

Question 29

Cytoplasm

Answer 29

composed of mainly water with dissolved substances, such as ions - cytosol cells chemical reactions take place within the cytoplasm

Question 30

Plasma membrane

Answer 30

surrounds the cell and encloses all the cell contents The membrane is responsible for controlling the interactions of the cell's interior with the exterior - Materials required by the cell are transported into the cell interior - Waste substances are exported out of the cell to the surrounding environment

Question 31

structures common to most prokaryotes

Answer 31

lack nucleus 70S ribosomes DNA in a loop Cytoplasm Plasma membrane Cell wall

Question 32

Ribosomes

Answer 32

protiensynthesis binding and reading of mRNA during translation to produce proteins found freely or in RER

Question 33

genetic material in prokaryotic cells

Answer 33

in the form of a "naked" single circular DNA molecule (not associated with proteins) located in the nucleoid and in smaller loops called plasmids

Question 34

Plasmids

Answer 34

small loops of DNA that are separate from the main circular DNA molecule - Plasmids contain genes that can be passed between prokaryotes (e.g. genes for antibiotic resistance)

Question 35

Cell wall

Answer 35

The cell wall acts as protection, maintains the shape of the cell and prevents the cell from bursting

Question 36

Additional structures of prokaryotic cells

Answer 36

Plasmids Capsules Flagellum Pili

Question 37

capsule

Answer 37

helps to protect bacteria from drying out and from attack by cells of the immune system of the host organism

Question 38

Flagellum

Answer 38

are long, tail-like structures that rotate, enabling the prokaryote to move

Question 39

Pili

Answer 39

They assist with movement, avoidance of attack by white blood cells, conjugation and are commonly used to allow bacteria to adhere to cell surfaces

Question 40

key differences between animal and plant cells

Answer 40

- Animal cells contain centrioles and microvilli - Plant cells have a cellulose cell wall, large permanent vacuoles and chloroplast

Question 41

nucleus

Answer 41

Present in all eukaryotic cells (except red blood cells), the nucleus is relatively large and separated from the cytoplasm by a double membrane which has many pores nucleus contains chromatin has nucleolus inside nucleus

Question 42

nucleolus

Answer 42

sites of ribosome production

Question 43

Rough endoplasmic reticulum

Answer 43

connected to nuclear envelope membrane used as a site for protien sythesis has ribosomes help makes polypeptides

Question 44

Mitochondria

Answer 44

The site of aerobic respiration within all eukaryotic cells small circular pieces of DNA and ribosomes also found in matrix

Question 45

Golgi apparatus

Answer 45

Flattened sacs of membrane called cisternae Modifies proteins and lipids before packaging them into Golgi vesicles prominent in metabolically active sites site of specific biochemicals

Question 46

Vesicles

Answer 46

A membrane-bound sac for transport and storage

Question 47

Lysosome

Answer 47

membrane bound vesicles containing digestive enzymes breakdown of food vacuoles digest pathogens engulfed by phagocytes

Question 48

non permanent vacuole

Answer 48

small vacuoles in animal cells used to temporarily store materials or to transport substances

Question 49

Chloroplasts

Answer 49

only plant cells site of photosynthesis - Membrane-bound compartments called thylakoids containing chlorophyll stack to form structures called grana - Grana are joined together by lamellae (thin and flat thylakoid membranes) - stroma - light independent stage

Question 50

Centrioles

Answer 50

- Hollow fibres made of microtubules - Not found in flowering plants and fungi

Question 51

Microtubules

Answer 51

Found in all eukaryotic cells Makes up the cytoskeleton of the cell and are about 25 nm in diameter Thirteen protofilaments in a cylinder make a microtubule

Question 52

cytoskeleton

Answer 52

The cytoskeleton is used to provide support and movement to the cell

Question 53

three main types of fibre in cytoskeleton

Answer 53

- microtubules - micro filaments - intermediate filaments

Question 54

Functions of Life

Answer 54

m - movement r- reproduction s- sensitivity g- growth r- response e- excretion n- nutrition

Question 55

Metabolism

Answer 55

all the enzyme-catalysed reactions occurring in a cell, including cell respiration

Question 56

Reproduction

Answer 56

the production of offspring. It may be sexual or asexual

Question 57

Homeostasis

Answer 57

the ability to maintain and regulate internal conditions within tolerable limits, including temperature

Question 58

Growth

Answer 58

the permanent increase in size and dry mass

Question 59

Response

Answer 59

the ability to respond to external or internal changes (stimuli) in their environment. Thus improving their chance of survival

Question 60

Excretion

Answer 60

the disposal of metabolic waste products, including carbon dioxide from respiration

Question 61

Nutrition

Answer 61

the acquisition of energy and nutrients for growth and development, either by, absorbing organic matter or by synthesising organic molecules

Question 62

Atypical Cell examples

Answer 62

Skeletal muscle, aseptate fungal hyphae, red blood cells and phloem sieve tubes are examples of cells/tissue with structures that question the integrity of the cell theory

Question 63

Striated muscle fibres

Answer 63

Longer than typical cells formed from multiple cells which have fused together (which is how they have many nuclei rather than one) that work together as a single unit

Question 64

Aseptate fungal hyphae

Answer 64

Fungi have many long, narrow branches called hyphae Hyphae have cell membranes, cell walls and some have septa Aseptate fungal hyphae do not have septa, thus these cells are multinucleated with continuous cytoplasm The cells have no end walls making them appear as one cell

Question 65

Red blood cells

Answer 65

Red blood cells, a type of animal cell, are unique in that they do not contain a nucleus and are concave transport of oxygen haemoglobin

Question 66

calculating of mag of an image using scale bar steps

Answer 66

1. measure scale bar in mm 2. convert measurement to um 3. divide measurement with number on top of scale bar

Question 67

calculation of size of specimen using scale bar steps

Answer 67

1. measure size of specimen in mm 2. measure scale bar in mm 3. divide specimen by scale bar 4. multiply answer with number written on the scale bar (um)

Question 68

calculation of size of specimen using magnification steps

Answer 68

1. measure specimen in mm 2. convert measurement to um 3. divide specimen length by magnification

Question 69

SER

Answer 69

RER without ribosomes makes lipids and cholesterol site of storage of calcium ions

Question 70

apoptosis

Answer 70

program cell death which occurs in cells damaged by infection or mutation lysosomes involved in this - the all burst

Question 71

tubulin simple defination

Answer 71

helically arranged globular protien

Question 72

tubulin functions

Answer 72

movement of chromosomes during cell division achieved by lengthening and shortening of microtubules maintains shape of cell guide and direct other components

Question 73

microfilaments

Answer 73

thinnest class of cytoskeletal fibres made of solid robs of globular protein called actin

Question 74

functions of microfilaments

Answer 74

involved in cleavage furrow formation to divide cell during cell division cell motility maintain and change cell shape

Question 75

spindle

Answer 75

structure formed by microtubules movement of chromosomes in mitosis and meiosis

Question 76

centrosomes

Answer 76

- Two centrioles at right angles to each other form a centrosome, which organises the spindle fibres during cell division near nucleus

Question 77

transport vesicles

Answer 77

move molecules between locations inside cells by budding off one organelle component and fusing with another

Question 78

secretory vesicles

Answer 78

secret molecules from the cell via exocytosis also how new phospholipids are added to cell membrane

Question 79

paramecium

Answer 79

fresh water eukaryotic organisms can carry out all life processes

Question 80

chlorella

Answer 80

algae found in freshwater ponds colours the water green

Question 81

chlamydomonas

Answer 81

eukaryotic organisms that live in soil, fresh water, oceans and snow

Question 82

autotrophs

Answer 82

can make their own food by using sources like the sun

Question 83

heterotrophs

Answer 83

can't make their own food and obtain it from other organisms

Question 84

features of fungus

Answer 84

cell wall of chitin uni or multi cellular saprotrophs parasitic can be decomposers

Question 85

saprotrophs

Answer 85

feed on non living decaying matter external digestion