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Biology Year 1 > Topic 2A- Cell Structure and Division + RP2 > Flashcards

Topic 2A- Cell Structure and Division + RP2 Flashcards

1
Q

Describe eukaryotic cells

A

complex
include plant and animal cells
also algae and fungi

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2
Q

Describe prokaryotic cells

A

small
simple
e.g. bacteria

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3
Q

Name three differences in structure between plant cells and animal cells

A
  • cellulose cell wall present in plant cell with plasmodesmata (channels for exchanging substances)
  • vacuole in plant cell (contains cell sap)
  • chloroplasts in plant cells
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4
Q

Describe the structure of algal cells

A

Similar to plant cells, same organelles including cell wall and chloroplasts

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5
Q

Describe the structure of fungi cells

A

Similar to plant cells, however, cell wall made of chitin, not cellulose
also don’t have chloroplasts

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6
Q

What is the cell-surface membrane made of?

A

mainly of lipids and protein

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7
Q

What is the function of the cell-surface membrane?

A

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

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8
Q

Describe the structure of the nucleus

A

large organelle surrounded by a nuclear envelope (double membrane) which contains many pores
contains many chromosomes, and also a nucleolus

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9
Q

What is the function of the nucleus? (4)

A

control’s the cell’s activities, by controlling transcription of DNA
contains instructions on how to make proteins
pores allow substances to move between the nucleus and the cytoplasm
nucleolus makes ribosomes

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10
Q

Describe the structure of a mitochondria

A

oval shaped
double membrane- inner one folded to form structures called cristae
inside is the matrix that contains enzymes involved in respiration

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11
Q

Describe the function of mitochondria

A

site of aerobic respiration
where ATP is produced
found in large numbers in cells that are very active and require lots of energy

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12
Q

Describe the structure of a chloroplast

A

small, flattened structure
surrounded by double membrane
has membranes inside called thylakoid membranes
thylakoid membranes can be stacked up to from grana
grana are linked together by lamellae

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13
Q

Describe the function of chloroplasts

A

site of photosynthesis
some parts of photosynthesis happen in the grana, and other parts happen in the stroma(thick liquid found in the chloroplasts)

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14
Q

Describe the golgi apparatus

A

group of fluid filled, membrane bound flattened sacs
vesicles often seen at the edge of sacs

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15
Q

Describe the function of the golgi apparatus

A

processes and packages new lipids and proteins
also makes lysosomes

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16
Q

Describe the structure of the Golgi vesicle

A

small fluid- filled sac in the cytoplasm, surrounded by a membrane

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17
Q

Describe the function of the golgi vesicle

A

stores lipids and proteins made by the golgi apparatus and transports them out of the cell

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18
Q

Describe the structure of a lysosome

A

a round organelle surrounded by a membrane
no clear internal structure

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19
Q

Describe the function of lysosomes

A

contains hydrolytic enzymes
these are kept separate from the cytoplasm by surrounding the membrane, and can be used to digest invading cells or to break down worn out components of the cell

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20
Q

Describe the structure of ribosomes

A

very small organelle either in cytoplasm or attached to rough endoplasmic reticulum
made up of proteins and RNA
not surrounded by membrane

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21
Q

Describe the function of ribosomes

A

site where proteins are made

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22
Q

Describe the structure of the RER

A

a system of membranes enclosing a fluid-filled space
surface covered with ribosomes

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23
Q

Describe the function of the RER

A

folds and processes proteins that have been made at the ribosomes

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24
Q

Describe the structure of the SER

A

a system of membranes enclosing a fluid-filled space
no ribosomes

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25
Q

Describe the function of the SER

A

synthesises and processes lipids

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26
Q

Describe the structure of the cell wall

A

rigid structure that surrounds cells in plants, algae, and fungi
made mainly of cellulose
in fungi, made of chitin

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27
Q

Describe the function of the cell wall

A

supports the cells and prevents them from changing shape

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28
Q

Describe the structure of the cell vacuole

A

membrane-bound organelle found in the cytoplasm of plant cells
contains cell sap (weak solution of sugar and salts)
surrounding membrane called the tonoplast

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29
Q

Describe the function of the cell vacuole

A

helps to maintain the pressure inside the cell and keeps the cell rigid
stops plants wilting
involved in the isolation of unwanted chemicals inside the cell

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30
Q

What are epithelial cells specialised to do?

A

absorb food efficiently

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31
Q

How are epithelial cells adapted for their function?

A

lots of mitochondria
folds on surface of cell called microvilli

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32
Q

What is a tissue?

A

a group of cells working together to perform a particular function

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33
Q

Give an example of how a cell can lead to an organ system

A

epithelial cell
lots of them make epithelial tissue
epithelial tissue, glandular tissue, muscular tissue make up the stomach (organ)
stomach part of digestive system (organ system)

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34
Q

How is the cytoplasm in a prokaryotic cell different to a eukaryotic cell?

A

the cytoplasm of a prokaryotic cell has no membrane bound organelles (unlike eukaryotic cells)
it has ribosomes but they’re smaller than those in a eukaryotic cell

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35
Q

What is the cell wall made from in a prokaryotic cell?

A

a polymer called murein
murein is a glycoprotein (protein with carbohydrate attached)

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36
Q

How can prokaryotic cells like bacteria protect themselves against attack from the immune system?

A

they can have a capsule made up of secreted slime, to protect the bacteria

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37
Q

What are plasmids?

A

small loops of DNA that aren’t part of the circular DNA molecule

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38
Q

What do plasmids contain?

A

they contain genes for things like antibiotic resistance, and can be passed between prokaryotes

39
Q

Where is DNA stored in a prokaryotic cell?

A

floating free in the cytoplasm, as circular DNA, its present as one long coiled up strand.
its not attached to any histone proteins

40
Q

What is the flagellum?

A

a long hair long structure that rotates to make the cell move

41
Q

Name three things about prokaryotic cells that are different to eukaryotic cells

A

-flagellum
- plasmids
- no nucleus
- no membrane bound organelles in the cytoplasm

42
Q

What is the structure of viruses?

A

nucleic acids surrounded by protein
viruses have no plasma membrane, no cytoplasm and no ribosomes

genetic material core of either DNA or RNA
protein coat around the core is called the capsid
attachment proteins stick out from the edge of the capsid.

43
Q

How do prokaryotic cells replicate?

A

binary fission

44
Q

Describe the process of binary fission

A
  1. the circular DNA and plasmid(s) replicate. the main DNA loop is replicated once, however plasmids can replicate lots
  2. the cell gets bigger and the DNA loops move to opposite ‘poles’ of the cell
  3. the cytoplasm begins to divide, and cell wall begins to form
  4. the cytoplasm divides and two daughter cells are produced. each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmid(s)
45
Q

Describe how viruses replicate themselves

A
  1. viruses use their attachment proteins to bind to complementary receptor proteins on the surface of host cells
  2. different viruses have different attachment proteins and therefore require different receptor proteins on host cells. as a result, some viruses can only infect one type of cell
  3. because they’re not alive, viruses don’t undergo cell division. Instead, they inject their DNA or RNA into the host cell, then use the cell to replicate the virus particles
46
Q

Define magnification

A

how much bigger the image is than the specimen

47
Q

What is the magnification equation?

A

I = A X M

48
Q

What is resolution?

A

how detailed the image is, how well a microscope distinguishes between two points that are close together

49
Q

What is the maximum resolution of an optical (light) microscope?

A

0.2 micrometers

50
Q

Why is the resolution of light microscopes a problem?

A

you cant see organelles at all/ in a lot of detail

51
Q

What is the max resolution of an electron microscope?

A

0.0002 micrometers

52
Q

What is the maximum magnification of a light microscope?

A

x1500

53
Q

What is the maximum magnification of an electron microscope?

A

x 1 500 000

54
Q

How do TEMs work?

A

TEMs use electromagnets to focus a beam of electrons, which is then transmitted through the specimen. Denser parts of the specimen absorb more electrons, which makes them look darker on the image you end up with.

55
Q

Give one strength and one weakness of using TEMs

A
  • high resolution, can see internal structures of organelles
  • only can be used on thin specimens
56
Q

Describe how SEMs work

A

SEMs scan a beam of electrons across the specimen, which knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image. The images you get show the surface of the specimen, and can be 3D

57
Q

Give one strength and one weakness of SEMs

A
  • can be used on thick specimens
  • give lower resolution images than TEMs
58
Q

Describe how to make a slide

A
  1. pipette small amount of water on slide
  2. place specimen on slide using tweezers
  3. add drop of stain
  4. add cover slip, try not to get air bubbles in it
59
Q

What are stains used for when making a slide?

A

used to highlight objects in a cell

60
Q

What are the three steps of cell fractionation?

A

homogenisation
filtration
ultracentrifugation

61
Q

What does cell fractionation do?

A

separates organelles

62
Q

Describe the first step of cell fractionation

A

homogenisation- breaking up the cells
can be done by vibrating the cells, or using a blender
this breaks up the plasma membrane and releases the organelles into solution
the solution must be kept ice cold and isotonic
a buffer solution should also be added to maintain pH

63
Q

Why should the solution be kept ice cold and isotonic during homogenisation?

A

ice cold- to reduce the activity of enzymes that break down organelles
isotonic- prevents damage to the organelles through osmosis

64
Q

What does isotonic mean?

A

the solution should have the same concentration as the chemicals being broken down, no movement of water (osmosis)

65
Q

Describe and explain the second step in cell fractionation

A

filtration- homogenised cell solution is filtered through a gauze to separate any large cell debris, or tissue debris

66
Q

Describe the final stage of cell fractionation

A
  1. pour cell fragments into a tube, and put into a centrifuge, and spin at low speed, pellet formed at the bottom, supernatant fluid above it
  2. supernatant drained off and spun again, at higher speed
  3. process repeated until all organelles separated out
67
Q

In ultracentrifugation, what are the first organelles to form a pellet?

A

the heaviest organelles e.g. nuclei

68
Q

Why is mitosis needed?

A

for growth of multicellular organisms and repairing damaged tissues

69
Q

What are the 4 stages of the cell cycle?

A
  1. mitosis
  2. gap phase 1
  3. synthesis
  4. gap phase 2
70
Q

What happens at gap phase 1?

A

cell grows and new organelles and proteins are made

71
Q

What happens at synthesis?

A

the cell replicates its DNA

72
Q

What happens at gap phase 2?

A

the cell keeps growing and proteins needed for cell division are made

73
Q

What are the four stages of mitosis?

A

Prophase
Metaphase
Anaphase
Telophase

74
Q

What is interphase?

A

The cell carries out normal functions, but also prepares to divide. the cell’s DNA is unravelled and replicated, to double its genetic content, the organelles are also replicated and ATP content is increased

75
Q

What is the centromere?

A

the point on a chromosome where spindle fibres attach to pull sister chromatids apart during cell division

76
Q

What are sister chromatids?

A

the two separate strands in a chromosome

77
Q

Describe what happens in prophase

A

the chromosomes condense, getting shorter and fatter
centrioles start moving to the opposite ends of the cell, forming a network of protein spindle fibres
the nuclear envelope breaks down and chromosomes lie free in the cytoplasm

78
Q

What are centrioles?

A

tiny bundles of protein

79
Q

Describe what happens in metaphase

A

the chromosomes line up along the middle of the cell and become attached to the spindle by the centromere

80
Q

Describe what happens in anaphase

A

the centromeres divide, and sister chromatids separate
the spindles contract, making the chromatids appear V shaped

81
Q

Describe what happens in telophase

A

the chromatids reach the opposite poles on the spindle, they uncoil and become long and thin again. they’re now called chromosomes again
nuclear envelope forms around chromosomes
division of the cytoplasm finishes, two daughter cells formed

82
Q

What is cytokinesis?

A

division of the cytoplasm
starts in anaphase, finishes in telophase

83
Q

How can you calculate mitotic index?

A

no. of cells in mitosis/ total number of cell x 100

84
Q

Describe how tumours are formed

A

if there’s a mutation in a gene that controls cell division, cells can then grow out of control

85
Q

What are the two types of tumour?

A

malignant
benign

86
Q

How does chemotherapy work?

A

it prevents the synthesis of enzymes needed for DNA replication, if these are produced the cell is unable to enter the synthesis phase (S)

87
Q

How can radiation prevent DNA replication, and therefor stop cancer?

A

it can damage DNA, the cell is checked for damage to DNA several times in the cell cycle, and if damage is detected the cell will kill itself, preventing tumour growth

88
Q

RP 2- Describe the method of investigating osmosis

A
  1. 1cm from the tip of a growing root
  2. put 1M hydrochloric acid in a boiling tube in a water bath at 60 C
  3. transfer root tip into boiling tube and incubate for 5 mins
  4. use a pipette to rinse the root tip well with cold water, leave to dry on paper towel
  5. place root tip on slide and 2mm from the very tip of it
  6. use a mounted needle to break the tip open and spread the cells out thinly
  7. add a few drops of stain and leave it for a few mins
  8. place cover slip over the cells and push down firmly to squash the tissue, this will make the tissue thinner and allow light to pass through it
89
Q

RP 2- Why does it need to be the root where you cut from?

A

because that’s where the growth occurs

90
Q

RP 2- What temperature does the water bath need to be at for the hydrochloric acid?

A

60 C

91
Q

RP 2- What chemical is put in the water bath?

A

1M hydrochloric acid

92
Q

RP 2- Why do we use a stain?

A

to make the chromosomes easier to see

93
Q

RP 2- What equation do we use to calculate the mitotic index?

A

no. of cell with visible chromosomes / total number of cells observed

Biology Year 1 (9 decks)

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