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A Level Biology Revision > Cells- Joseph Felton > Flashcards

Cells- Joseph Felton Flashcards

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1
Q

Recall the structure and explain what is meant by a eukaryotic cell and the defining characteristics of a eukaryotic cell?

A

A eukaryotic cell has a membrane-bound nucleus and organelles.

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2
Q

Explain the role of cell-surface membranes within eukaryotic cells?

A

A permeable layer which controls entry and exit of substances.

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3
Q

Explain the role of the nucleus within eukaryotic cells?

A

The nucleus contains the hereditary material and controls the cell’s activities.

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4
Q

Explain the role of the mitochondria within eukaryotic cells?

A

Site of aerobic respiration, responsible for ATP production.

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5
Q

Explain the role of the Golgi apparatus in eukaryotic cells?

A

A stack of membranes, creates glycoproteins, modifies and transports lipids and modified proteins via exocytosis.

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6
Q

Explain the role of vesicles within eukaryotic cells?

A

Vesicles transport lipids and glycoproteins from the Golgi apparatus to the cell-surface membrane where they are released to the outside of the cell via exocytosis.

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7
Q

Explain the role of lysosomes in eukaryotic cells?

A

Lysosomes are vesicles that contain lysozymes which hydrolyse cell walls of bacteria.

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8
Q

Explain the role of rough and smooth ER in eukaryotic cells?

A

RER-provides large surface area for protein synthesis and contains ribosomes.
smooth ER- lacks ribosomes, synthesise, store and transport carbs and lipids.

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9
Q

Explain the role of chloroplasts in eukaryotic cells?

A

Carry out photosynthesis, contain stacks of thylakoid discs called grana. In thylakoids is photosynthetic pigment called chlorophyll.

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10
Q

Explain the role of the cell wall in eukaryotic cells?

A

Provides mechanical strength for the plant as a whole, also prevents cell from bursting under pressure via osmosis.

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11
Q

Explain the role of the cell vacuole in eukaryotic cells?

A

Fluid-filled sac containing minerals, acts as a temporary food store, can make cells turgid.

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12
Q

Identify examples of specialised eukaryotic cells and explain common adaptations that cells have to particular functions?

A

A sperm cell will have a large number of mitochondria to produce Large amounts of ATP for fast movement, phagocytes will have a large number of lysosomes to effectively combat pathogens.

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13
Q

Describe the organisation of cells into tissues, organs and organ systems?

A

Cells aggregate into tissues. Tissues aggregate into organs, organs aggregate into organ systems.

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14
Q

Describe structural differences between prokaryotic and eukaryotic cells?

A

Eukaryotic cells have a distinct nucleus and DNA that is associated with proteins, also membrane-bounded organelles. Prokaryotic cells have no nucleus or protein-associated DNA, no membrane-bound organelles.

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15
Q

Explain the purpose of plasmids?

A

Possesses genes and enzymes that break down antibiotics.

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16
Q

Explain the purpose of capsules?

A

Protects bacteria from other cells, and helps bacteria stick together for protection.

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17
Q

Explain the purpose of flagella?

A

Allows movement for bacterium and viruses.

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18
Q

Describe the structure of virus particles?

A

Capsid, attachment proteins, enzyme, matrix, lipid envelope, RNA (genetic material)

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19
Q

Explain the role of the capsid?

A

A protein coat that encloses RNA.

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20
Q

Explain the role of attachment proteins?

A

Allows virus to identify and attach to a host’s cells.

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21
Q

Relate the structure of a virus to its replication within cells?

A

Attachment proteins allow the identification and attachment to a host’s cells. Enzyme allows the virus to convert its own RNA into DNA for host’s cell, Capsid fuses with cell-surface membrane.

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22
Q

Describe how a light microscope works?

A

Shines a bright light through a cross section of a thin specimen.

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23
Q

Describe how electron microscopy works?

A

TEM-A beam of electrons is focussed onto a thin specimen and the beam passes through and is absorbed by different parts of specimen.
SEM- Directs a beam of electrons on to the surface and then passes the beam back and forth, scattering of electrons causes an image to be produced.

24
Q

Limitations and benefits of both forms of microscopy?

A

ADV- light microscope cheap and allows basic structures to be seen, electron microscopy produces cell ultrastructure.
DADV-light microscopy produces poor magnification, electron microscopy very expensive and sample must be viewed in vacuum.

25
Q

What is magnification?

A

How many times bigger the image is than the actual object.

26
Q

What is resolution?

A

The process of reducing or separating something into constituent parts or components.

27
Q

What is cell fractionation?

A

Where cells are broken up and the different organelles are separated.

28
Q

Describe the solution that the sample is placed in?

A

Cold- to reduce enzyme activity
Isotonic- prevent osmotic loss or gain
Buffered- maintain pH

29
Q

What happens during homogenisation?

A

Cells are broken up by a homogeniser releasing the organelles from the cell. Homogenate then filtered removing debris and whole cells.

30
Q

What happens during ultracentrifugation?

A

Filtrate placed in centrifuge and spun at low speeds, heaviest organelles removed, supernatant removed and spun faster removing lighter organelles.

31
Q

Explain the role of the ribosomes in eukaryotic cells?

A

Contain ribosomal RNA and protein and are the site of protein synthesis.

32
Q

Explain what the cell cycle is?

A

Cell cycle is the process of events that leads to the production of two daughter cells from one parent cell.

33
Q

Identify the stages of the cell cycle?

A

Prophase, metaphase, anaphase, telophase.

34
Q

What is interphase?

A

When DNA replication occurs.

35
Q

What happens during prophase?

A

Chromosomes become visible and nucleolus dissolves, spindle fibres develop from centrioles.

36
Q

What happens during metaphase?

A

Spindle fibres attach to centromeres of chromosomes and arrange them along the equator of the cell.

37
Q

What happens during anaphase?

A

Centromeres divide into two and the spindle fibres pull chromatids to opposite poles of the cell, energy provided by mitochondria.

38
Q

What happens during telophase?

A

Chromosomes reach the ends of their poles and disperse into chromatin, spindle apparatus dissolves. Nucleolus and nuclear envelope re-form.

39
Q

What happens during cytokinesis?

A

Cytoplasm divides into two cells.

40
Q

Describe uncontrolled cell division and explain how it can lead to the formation of tumours and cancers?

A

Caused by damage to genes that regulate mitosis leading to formation of a group of abnormal cells called a tumour, malignant tumours are cancerous.

41
Q

Explain the processes within the cell cycle which are disrupted and which lead to cancer?

A

DNA replication in interphase becomes disrupted by mutations of the genes. Leads to formation of abnormal cells.

42
Q

Explain how cancer treatments often work to inhibit stages of the cell cycle?

A

Chemotherapy involves preventing DNA replication and interfering with spindle fibre formation during metaphase.

43
Q

Explain what binary fission is and describe how it occurs in prokaryotic cells?

A

Plasmids and circular DNA replicate, both copies attach to the membrane, membrane grows between two DNA molecules and pinches inward.

44
Q

Explain how viruses are not classified as being living organisms?

A

They cannot undergo cell division and instead replicate within a host’s cell.

45
Q

Describe the sequence of events by which viruses replicate?

A

They attach to their host’s cell via attachment proteins, capsid fuses with membrane of cell, viral RNA injected into nucleus, Cell produces viral components via metabolic processes.

46
Q

Explain why viruses are so difficult to treat and develop medicines against?

A

Viruses hide themselves within host’s cells and replicate, antibiotics won’t target host’s cells.

47
Q

Describe the fluid mosaic model of cell membranes?

A

Fluid- phospholipids can move allowing membrane to constantly change shape.
Mosaic- protein embedment varies in shape and size.

48
Q

Explain the role and importance of phospholipids in cell membranes?

A

Allow lipid-soluble substances to enter and leave cell, Prevent water-soluble substances entering and leaving the cell.

49
Q

Explain the role and importance of proteins in cell membranes?

A

Provide structural support, channel and carrier proteins allow facilitated diffusion, act as hormone receptors.

50
Q

Explain the role and importance of cholesterol in cell membranes?

A

Prevent leakage of water and dissolved ions from the cell, make membrane less fluid at high temperatures.

51
Q

Explain the role and importance of glycolipids in cell membranes?

A

Act as recognition sites, help maintain stability of membrane.

52
Q

What are glycolipids?

A

Carbohydrate covalently bonded to a lipid.

53
Q

Explain the role and importance of glycoproteins in cell membranes?

A

Act as recognition sites, allow cells to recognise each other.

54
Q

What are glycoproteins?

A

Carbohydrate chain attached to extrinsic proteins.

55
Q

Describe and explain the movement of water across partially permeable membranes by osmosis?

A

Water will move by osmosis from a region of high water potential to a region of less water potential.

A Level Biology Revision (10 decks)

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