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biology > cells > Flashcards

cells Flashcards

1
Q

What is cell ultrastructure?

A

The study of organelles

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2
Q

What is the structure of the nucleus?

A

. Spherical, 10-20um
. Phospholytic bilayer membrane
. Nucleolus
. Nuclear membrane has many pores
. Outer membrane folded to form RER

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3
Q

What is the function of the nucleus?

A

. Store DNA (preventing damage in cytoplasm)
. Nucleolus manufactures rRNA and ribosomes
. Controls cell activities through production of mRNA
. nuclear pores allow mRNA to leave nucleus

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4
Q

What information leads scientists to believe mitochondria had a bacterial origin?

A

. Loops of DNA
. Shape and size
. No membrane- bound organelles

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5
Q

What tissues contain lots of mitochondria?

A

Muscle tissue and epithelial tissue (SI)

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6
Q

What is the structure of the mitochondria?

A

. Rod shaped, 1-10um
. Has cristae- folds of inner membrane
. Membrane- bound organelles
. Prokaryotic style DNA and ribosomes

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7
Q

What is the function of the mitochondria?

A

. To produce energy through cellular respiration
. Synthesise ATP
. Oxidative phosphorylation
. Own DNA for replication
. Cristae provide large SA for enzymes

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8
Q

What is the function of lysosomes?

A

. To degrade material taken up from outside the cell and to digest obsolete components of the cell itself
. Formed by golgi apparatus
. Up to 1um in diameter
. Contains hydrolytic enzymes (proteases and lipases)
. Breaks down materials from phagocytosis
. Enzyme exocytosis
. Cell autolysis
. Isolate harmful enzymes from rest of cell

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9
Q

what is the structure of RER?

A

. folds of membrane, encrusted with ribosomes
. large SA- proteinsynthesis
. connected to nucleus membrane
. membranes enclosed, flattened sacs called cisternae

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10
Q

what is the function of RER?

A

. proteinsynthesis (cells destined for export are synthesised)
. provides large SA
. provides pathway for transport of proteins

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11
Q

what is the structure of SER?

A

. similar to RER but more tubular
. continuous to RER

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12
Q

what is the function of SER?

A

. synthesise, store and transport lipids and carbohydrates

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13
Q

what is the structure of golgi apparatus?

A

. similar to SER but more compact
. flattened sacks called cisternae and small, hollow vesicles
. found extensively in epithelial cells

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14
Q

what is the function of golgi apparatus?

A

. recieving, sorting and delivering proteins and lipids
. modifying by adding non-protein components
. forms lysosomes
. vesicles carry finished product to fuse with cell surface membrane

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15
Q

what is the structure of ribosomes?

A

. located in RER or free in cytoplasm
. smallest organelle
. prokaryotes have 80s ribosomes
. eukaryotes have 70s ribosomes
. have a large and small subunit (rRNA and protein)
. can account for 25% of dry mass of a cell

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16
Q

what is the function of ribosomes?

A

. proteinsynthesis
. ribosomes on RER produce proteins designed for export
. free ribosomes in cytoplasm
. produce proteins for cellular use

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17
Q

what plant cell has no chloroplasts and why?

A

. root hair cell
. underground and so doesnt recieve any sunlight

18
Q

what is the structure of a chloroplast?

A

. disc-shaped plant organelle around 2-10nm length and 1nm diameter
. double phospholipid membrane
. stroma- like cytoplasm
. thykaloid discs contain chlorophyll forming stacks of granum up to 100 discs
. intergranullar lamella
. ribosomes, loop of DNA, starch

19
Q

what are the function of chloroplasts?

A

. production of glucose stored as starch
. ribosomes and DNA allow chloroplasts to quickly produce proteins needed
. LDR- 1st stage, takes place on glana (large SA and attached chlorophyll, enzymes)
. LDR- takes place in stoma , enzymes

20
Q

what is the structure of leaf pallisade cells?

A

. elongated
. large numbers of chloroplasts
. migrate to areas of greatest LI
. thin cell walls for efficient diffusion of co2

21
Q

what is the structure of a vacuole?

A

. large and central
. composed of membranes containing cell sap
. helps to maintain turgour pressure
. used for storage

22
Q

what is G1?

A

cell increases in size (growth phase)

23
Q

what is S phase?

A

cell replicates DNA

24
Q

what is G2?

A

the cell increases further in size and replicates organelles

25
Q

what is M phase?

A

mitosis

26
Q

what is interphase?

A

cell doing its usual jobs

27
Q

what are the stages of mitosis?

A

. prophase
. metaphase
. amaphase
. telephase
. cytokenesis

28
Q

what are the steps of ultracentrifugation?

A

. break up cell to create hemogenate
. filter to remove any whole cells
. increase G force
. densest parts form pellet
. repeat
. liquid on top called supernatant

29
Q

what is the structure of bacteria?

A

. have cell walls- made of murein
. some have outer layer called capsule for protection and to stick to other bacteria
. plasmids contain genes that improve survival
. plasmids can be easily exchanged between bacteria

30
Q

What is the magnification equation?

A

I = A × M

31
Q

What are the principles of a light microscope?

A

Visible light passes through the specimen and is bent through the lense system, allowing the user to see a magnified image

32
Q

What are the advantages of a light microscope?

A

. Living and dead material can be viewed
. Doesn’t require specialist training in order to operate
. Small and portable
. Unaffected by magnetic fields

33
Q

What are the limitations of a light microscope?

A

. Low resolution: limit is 200nm and so objects smaller cannot be viewed
. Low magnification: maximum is 1500x so is useless for small organelles
. Specimen may be disfigured while being prepared
. Most cells need to be stained to be seen

34
Q

What are the principles of TEM?

A

Used to examen thin slices of cell tissues, it projects an electronic beam through a sample and a 2D image is formed

35
Q

What are the advantages of TEM?

A

. They provide high resolution images with more detail
. They have a magnification of 1000000x
. They can view the internal structures of cells

36
Q

What are the limitations of TEM?

A

. Must be positioned in a vacuum, very detailed images of cell organelles and living specimens cannot survive so cannot visualise living material
. Can only be used for thin tissues as thick specimens easily absorb the electrons
. Can only use dead specimens

37
Q

What are the principles of SEM?

A

Scan a beam of electrons across the specimen, the beam bounces off the surface and electrons are detected, forming an image

38
Q

What are the advantages of SEM?

A

. They can be used on thick or 3D specimens
. They allow the external, 3D structure of specimens can be observed
. Large depth of field, examination of surface structure
. Resolution as low as 15nm
. Chemical analysis

39
Q

What are the limitations of SEM?

A

. Lower resolution than TEM
. They cannot be used to observe live specimens
. They do not produce a colour image
. Expensive to buy and run
. Small risk of radiation exposure

40
Q

What is binary fission?

A

Bacterial cell division is much more simple than mitosis because instead of chromosomes, they have a singular, circular DNA molecule
Plasmids are also replicated and passed on

41
Q

What are the stages of binary fission?

A
  1. dna replication of bacterial chromosome and plasmids
  2. cell divides into two, each receiving half the cytoplasm, one chromosome and some plasmids
42
Q

What is replication in viruses?

A

. Acellular and non-living so do not carry out cell division in any form
. Instead, they inject nucleic acid into a host cell
. The host cells dna-replicating and protein-synthesising systems make more virus particles
. Eventually, they are released when host cell bursts, or by each new virus leaving through cell membrane
. The host can be prokaryotic or eukaryotic

biology (8 decks)

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