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2A Flashcards

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1
Q

what is magnification

A

how much bigger a sample appears to be under the microscope than it is in real life

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2
Q

what is resolution

A

the ability to distinguish between two points on an image.

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3
Q

what are the advantages of an electron microscope

A

the resolution in x2000 more than LM microscope
it produces detailed images
SEM produces 3D image

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4
Q

what are the disadvantages of an electron microscope

A

Samples have to be placed in a vacuum
very expensive
need to be highly skilled to create samples
complex staining process
image may contain artefacts

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5
Q

what is the equation for magnification

A

magnification=size of image/size of the object

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6
Q

What do Transmission electron Microscope do

A

pass a beam of electrons through the sample.

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7
Q

What are the limitations of a Transmission electron microscope

A

Thin sections of specimen are needed for TEM as the electrons have to pass through the specimen for the image to be produced

flat 2D image

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8
Q

What do Scanning electron microscopes do

A

pass a beam of electrons over the surface, the electrons are then reflected off the surface of the specimen

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9
Q

what are the limitations of scanning electron microscope

A

The resolution is lower then that of the transmission electron microscope

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10
Q

what is cell fractionation

A

The process where cells are broken up and the different organelles they contain are separated

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11
Q

what is cell fractionation used for

A

Used to help us study cell structure and function

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12
Q

what is momogenisation

A

breaking up the cells

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13
Q

what is a centrifuge used for

A

separating the cell components

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14
Q

Before cell fractionation can begin what must happen

A

the tissue is placed in, cold, isotonic, buffer solution

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15
Q

why must the tissue be cold

A

to reduce enzyme activity, which may break down organelle

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16
Q

what is the role of isotonic solution

A

to prevent the organelle from bursting/ shrinking due to osmotic gain/ loss of water

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17
Q

what is the role of the solution being buffered

A

to maintain a constat PH

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18
Q

what is differential centrifugation and why does it happen in the experiment.

A

The size and density of any organelle is relatively constant so they all separate at a specific speed. Since the whole process involves centrifuging at different speeds it is called differential centrifugation.

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19
Q

In what order is the organelle separated during centrifugation

A

it happens in the order of most to least dense. Nuclei, chloroplast and mitochondria, lysosomes and endoplasmic reticulum, ribosomes

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20
Q

what is a graticule

A

a series of fine lines in the eyepiece of an optical device, such as a microscope, used as measuring scale. It enables scientists to estimate accurately the size of objects viewed under a microscopes.
does not change in size

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21
Q

what are the steps of cell centrifugation

A

1 chop up fresh tissue in ice cold, isotonic buffer solution.
2 Put the chopped tissue in a blender or homogeniser to break open the cells.
3 Filter the mixture to remove the debris, such as connective tissue and plant cell walls.
4 Pour the mixture into tubes and spin very quickly in a centrifuge.
5 The liquid layer on the top ( the supernatant ) is poured in to a fresh tube, leaving the pellet behind.
6 The supernatant may then be spun again at a faster rate to produce a sediment containing mitochondria and at an even higher speed for other organelle

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22
Q

what is the supernatant

A

The liquid layer on the top off the pellet, in centrifugation.

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23
Q

what is the cell membrane made out of

A

Phospholipids

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24
Q

How to prokaryotic cells differ from eukaryotic cells

A

Prokaryotic cells do not have a nucleus, whereas eukaryotic cells do. Prokaryotic cells also do not have a cell membrane

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25
Q

what are prokaryotic, plant and fungal cell walls made from

A

prokaryotic- peptidoglycan
fungal- chitin
plant- cellulose

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26
Q

what is a plasmid

A

a circular loop of DNA that contains their genetic material

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27
Q

what is a nucleoid

A

A space within a prokaryotic cell where DNA is found

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28
Q

what is the procedure for the calibration of a cell

A

1 put in the eyepiece
2 put on the stage micrometer
3 align them to calibrate
4 count divisions on the EPG = how many divisions on the micrometer
5 with the scale of the micrometer, find the length of each division on the EPG ( division on micrometer/divisions on EPG)
6 remove micrometer from stage
7 Put a cell slide on the stage
8 Measure EPG division that a cell accounts for
9 cell length = length of each division on EPG x number of EPG divisions of cell.

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29
Q

what is the structure and function of a nucleus for eukaryotic cells

A

structure: surrounded by a nuclear envelope (double membrane with pores), and it contains chromosomes (genetic material) and a dense solid structure called a nucleolus which is involved in ribosome synthesis.

Function: It contains the genetic information for the cells (including chemical reactions and cell division). It also controls when mRNA is produced, and hence controls protein production.

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30
Q

What is the structure and function of the different types of endoplasmic reticulum in a eukaryotic cell

A

structure: surrounds the nucleus, rough ER has ribosomes, smooth ER doesn’t

function of rough ER: site of protein synthesis

function of smooth ER: site of lipid and carbohydrate metabolism including hormone synthesis.

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31
Q

what is the structure and function of the Golgi apparatus in a eukaryotic cell

A

structure: flattened disc shaped sacs that are stacked on top of each other.

function: processed; carbohydrate may be added to proteins
Packaged: protein wrapped in a membrane vesicle
transported: vesicles move elsewhere in the cell
modified.

32
Q

what is the structure and function of the plasma membrane in a eukaryotic cell

A

structure- a bilayer that is made of phospholipids
function- controls the movement of substances in and out the cell

33
Q

what is the structure and function of mitochondria in a eukaryotic cell

A

structure-inner membrane is folded into eristae- where ATP is generated in the cell by aerobic respiration
the fluid inside is called the matrix- and contains energy for respiration
the no. of mitochondria depends upon the cells metabolic activity (sperm cells need more to move)

function- bounded by a double membrane, responsible for producing ATP (free energy) in respiration.

34
Q

what is the structure and function of lysosomes in a eukaryotic cell

A

structure- small sphere of liquid surrounded by a membrane
pinched off areas of the Golgi apparatus
function- contain enzymes that break down and hydrolyse food and foreign matter in cells.
They digest the cell after it dies and hydrolyse pathogens.

35
Q

What is the structure and function of ribosomes in a eukaryotic cell

A

structure- small structures that can be associated with ER or free within the cells cytoplasm
function- involved in protein synthesis, they assemble amino acids in the right order to produce new proteins.

36
Q

what are the two types of ribosomes and where are they found, and why are they different sizes

A

80s ribosomes- eukaryotes
70s ribosomes- prokaryotes

they are different sizes because prokaryotic cells are smaller, therefore needing smaller ribosomes

37
Q

what is the structure and function of chloroplasts

A

structure- disc shaped structure with a double membrane.
function- to carry out photosynthesis produce energy through photosynthesis and oxygen-release processes, which sustain plant growth and crop yield.

38
Q

what is the structure and function of a cell wall in a eukaryotic cell

A

structure- consists of cellulose membrane embedded in a matrix
middle lamella is the junction between one cell and the next which sticks the cells together
function- gives the cell strength. Prevents the cell bursting under osmotic pressure.

39
Q

what is the structure and function of a vacuole in a eukaryotic cell

A

structure- large permanent vacuole surrounded by a membrane called the lonoplat- contains sugars, salts, wastes and pigments
function- supports the cell by making cells turgid, acts as temporary food storage
provides colour

40
Q

what do single celled organisms have

A

Larger surface area to volume ratio
all cells are exposed to the environment
Effective exchange surface for gases, nutrients and waste, by simple diffusion

41
Q

what do all cells perform

A

Movement
respiration
sensitivity
control
growth
reproduction
excretion
nutrition

42
Q

what are the traits of multi cellular organisms

A

smaller surface area to volume ratio
not all cells in contact with external environment, therefore specialised cells have to perform different functions

43
Q

what is differentitation

A

when a cell becomes specialised to carry out a particular function.

44
Q

what are the categories of differentiation

A

1) change number of particular organelles- muscle cells have more mitochondria.
2) change shape of the cell( root hair cell- more surface area)
3)change co tents of the cell(e.g red blood cell xnucleus)

45
Q

what is the role of xylem+phloem and how is it adapted for this role.

A

dead cells, phocilitating water

transports minerals and sugars up and down the plant.

46
Q

what are the different levels of organisation and there definitions

A

tissue: groups of the same type of cells that perform the same function( muscle tissue in animals)
organ: groups of different tissues that perform a common function( stomach consists of mucus membrane tissue)
organ system:groups of different organs that perform a common function- respiratory system- muscle diaphram

47
Q

how are the cells on a a Erythrocyte specialised(red blood cell)

A

biconcave shape: increases surface area over which oxygen can be absorbed
cytoplasm-high amounts of permanent haemoglobin which binds with oxygen
no nucleus present- more space inside cell for haemoglobin molecules

48
Q

how are the cells on a Neutrophil specialised( white blood cell)

A

very flexible shape, allows them to squeeze through cell junctions in the capillary wall and engulf microorganisms
more lysosomes- help to digest and destroy invading cells
flexible nuclear membrane- further helps the cell to penetrate cell junctions

49
Q

how is a sperm cell specialised

A

head contains a nucleus, which contains half the normal number of chromosomes
acrosome(head)- contains digestive enzymes that can bread down the egg cell wall.
mid piece- packed with mitochondria to release energy for tail movement
tail- rotates propelling the sperm cell forward

50
Q

how is a palisade cell specialised

A

large no. of chloroplasts- site of photosynthesis-maximises the absorption of light
tall+ thin shape- allows light to penetrate deeper before encountering another cell wall. ( cell walls absorb/reflect light), cells densly packed together.

51
Q

how are the root hair cells specialised for their functions

A

elongated to increase surface area, the the uptake of water by osmosis is greater
thinner walls than other plant cells- osmosis easier
Permanent vacuole- contains sap- more concentrated than soil water maintaining water potential

52
Q

how are guard cells specialised

A

open in the daytime- use water for photosynthesis.
inner cell walls thicker, while outer cell walls thinner - allows cells to bend when turgid
cytoplasm- high density of chloroplasts .
mitochondria- play role in opening the stomata.

53
Q

how are ciliated epithelial cells specialised (throat)

A

cilia- hair like structures, that beat in coordinated way to shift materials along the surface of the epithelium tissue.
goblet cells(mucus secreting cells)- secrete mucus which helps to trap dust, dirt and microorganism- preventing them from entering vital organs where they might cause infection.

54
Q

what is the role off plasmids in a prokaryotic cell

A

contain genetic material such as antibiotic resistance

55
Q

what is the role of the slime capsule in a prokaryotic cell

A

helps to protect bacteria from attack by cells of the immune system

56
Q

what is mitosis

A

cell division that produces genetically identical cells

57
Q

what are the two types of cell division in eukaryotic cells

A

mitosis and meiosis

58
Q

what happens in mitosis

A

a parent cell divides to produce two genetically identical daughter cells

59
Q

why is mitosis needed

A

for growth of multicellular organisms, and for repairing damaged tissues

60
Q

what does the cell cycle consist of, and what happens in the stages

A

growth phase 1- this is where the cell growths and new organelles and proteins are made

synthesis- cell replicates its DNA ready to divide for mitosis

growth phase 2- cell keeps growing and proteins needed for cell division are made

mitosis- the start and end of the cell cycle

61
Q

what are the four stages of mitosis

A

prophase
metaphase
Anaphase
telophase

62
Q

what happens in the interphase

A

cell prepares to divide
DNA is unravelled and replicated, to double its genetic content. Organelles are also replicated, and ATP content is increased to provide energy for mitosis to happen.

63
Q

what happens in prophase

A

Chromosomes condense, getting shorter and fatter. Tiny bundles of protein called centrioles start moving to opposite ends of the cell, forming a network of protein fibres called spindle fibres. Nuclear envelope breaks down and chromosomes lie free in the cytosoplasm

64
Q

what happens in metaphase

A

the chromosomes line up along the equator of the cell and become attached to the spindle fibres by their centromere

65
Q

what happens in the anaphase

A

The centromeres divide, separating each pair of sister chromotads. The spindles contract, pilling chromotads to opposite poles of the spindle, centromere first

66
Q

what happens in the telophase

A

chromatids reach opposite poles of the spindle. They uncoil and become long and thin again. Nuclear envelope forms around each group of chromosomes, so there are now two nuclei. cytokinesis finishes. now two genetically identical daughter cells.

67
Q

what is mitosis controlled by

A

genes

68
Q

how does cancer form

A

if there is a mutation in a gene that controls cell division, the cell grows out of control. Cells keep dividing to make more and more cells, resulting in a tumour. Cancer is a tumour that invades other tissue. result of damage to the genes that control mitosis and cell division

69
Q

how can some cancer treatment target cell cycle

A

control the rate of cell division by disrupting the cell cycle. this kills the tumour cells.

70
Q

What is G1

A

some chemical drugs prevent the synthesis of enzymes needed for DNA replication. if these aren’t produced- cell is unable to enter the synthesis phase. disrupting the cell and forcing it to kill itself

71
Q

what is S phase

A

Radiation and some drugs damage DN. several point in the cell cycle the cell is checked for damage. If it is detected, the cell will kill itself, preventing tumour growth.

72
Q

wha are the names of the genes that control cell division

A

tumour suppressor genes-repress the cell cycle and promote apoptosis. less cell division.

porto-oncogenes- promote the cell cycle and stimulate cell division

both ensure cell divides at a fairly constant rate.

73
Q

what are benign tumours

A

cells are not cancerous
tumour cell division is slower than malignant
tumours do not invade tissues to firm secondary tumours.
moist of the time harmless
sometimes cause blockages
put pressure on organs
removed by surgery

74
Q

what are malignant tumours

A

cells are cancerous
divide by mitosis
tumour cell division is uncontrolled
cells can spread to other tissues to for secondary tumours by metastasis via blood or lymph system
requires radiotherapy or chemotherapy as well as surgery.

75
Q
A

biology Miss Ho (2 decks)

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