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Cell Structure 2.1 Flashcards

1
Q

What is the function of the nucleus?

A

-Contains genetic information
-Provides the instructions for protein synthesis

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2
Q

What is the structure of the nucleus?

A
  • nuclear envelope( double membrane with pores that allow entry and exit of substances e.g exit of MRNA)
    -nucleolus (has no membrane) where ribosomes are made
    -contains the genetic material chromatin
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3
Q

What is the function of the rough endoplasmic reticulum?

A

-transports assembled proteins through cisternae into vesicles to be transported into the Golgi apparatus

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4
Q

What is the structure of the rough endoplasmic reticulum?

A

-System of membranes, containing cisternae that are continuous with the nuclear membrane
-Provides a large surface area for ribosomes
-The RER is coated with ribosomes

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5
Q

What is the function of the smooth endoplasmic reticulum?

A

-Involved in lipid metabolism:
.Synthesises cholesterol
.Synthesises lipids and phospholipids needed by cell
.Synthesises steroid hormones .e.g. sex hormones

-Involved with absorption, synthesis and transport of lipids (from the gut)

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6
Q

What is the structure of the smooth endoplasmic reticulum?

A

-System of membranes ,containing cisternae that are continuous with the nuclear membrane
-No ribosomes on surface(unlike RER)
-Contains enzymes that catalyse reactions involved with lipid metabolism

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7
Q

What is the function of the Golgi apparatus ?

A

-Proteins are modified .e.g. by adding sugar molecules to make glycoproteins, being folded into their 3D shape
-Packages proteins into vesicles either for exocytosis or to be stored in cell

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8
Q

What is the structure of the Golgi apparatus?

A
  • Consists of stacks of membrane-bound flattened sacs
  • Secretory vesicles bring materials to and from the Golgi apparatus
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9
Q

What is the function of ribosomes?

A

PROTEIN SYNTHESIS

-ribosomes bound to exterior of RER mainly for synthesising proteins to be exported out of cell
-ribosomes free in the cytoplasm are primarily sight of assembly of proteins to be used inside of cell

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10
Q

What is the structure of ribosomes?

A

-Small spherical organelles (around 20nm in diameter )
-made of ribosomal RNA
-Made in nucleolus as two separate subunits, which pass through nuclear envelope into cytoplasm and then combine
-Some ribosomes are free in cytoplasm and some attach to RER

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11
Q

What is the function of mitochondria?

A

AEROBIC RESPIRATION

  • site of ATP ( energy currency) production during aerobic respiration
    -self replicating more can be made if the cells energy needs to increase
    -abundant in cells where much metabolic activity takes place .e.g. in liver cells and muscle cells
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12
Q

What is the structure of Mitochondria?

A

-May be spherical rod shaped or branched
-2-5micrometers long
- double membrane
- inner membrane highly folded ( folds called cristae)
-fluid filled matrix
- has DNA

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13
Q

What is the function of lysosomes?

A

BREAKS DOWN WORN OUT ORGANELLES

-keeps powerful hydrolytic enzymes separate from rest of cell
-engulfs old cell organelles and foreign matter ,digest them and return digested components to cell for reuse

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14
Q

What is the function of chloroplasts ?

A

-site of photosynthesis

1.light dependent stage (in grana)
2.light independent stage (in stroma)

Abundant in leaf cells, particularly the palisade mesophyll layer

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15
Q

What is the structure of chloroplasts?

A

-large organelles 4-10micrometers long
-double membrane
-inner membrane -stacks of thylakoids (which contains chlorophyll)
-each stack is called a granum (plural grana)
-fluid filled matrix called stroma
-contains loops of DNA and starch grains

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16
Q

What is the function of the cell plasma membrane?

A

-controls entrance and exit of molecules
-barrier
-selectively permeable
- phospholipid bilayer

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17
Q

What is the structure of the cell plasma membrane?

A

-2 layers of phospholipids
-contains proteins (cell signalling)
-contains cholesterol

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18
Q

What is the function of centrioles?

A

-makes spindle fibres (made out of tubulin) before a cell divides
-involved in the formation of cilia and undulipodium

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19
Q

What is the structure of centrioles?

A
  • consist of 2 bundles of microtubules at right angles to each other
    -microtubules are made of tubulin protein subunits and are arranged to form a cylinder
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20
Q

What is the function of a cell wall?

A

-not in animal cells , is strong and can prevent plant cells from bursting
-fully permeable
-provides strength and support
-maintain the cells shape

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21
Q

What is the structure of the cell wall?

A
  • made of cellulose fibres(in plants)
  • made of chitin in fungi
    -can include plasomdesmata(gaps in cell wall for exchange between cells)
22
Q

What is the function of flagella?

A

. Flagella help the cell move. Flagella also have microtubules inside of it like cilia, which contract to help the flagella move. This type of movement propels the cell and allow it to be mobile

23
Q

What is the function of cilia?

A
  • epithelial cells lining your airways each have many hundred of cilia that beat and move the band of mucus
    -nearly all cell types in your body have one cilium that’s act as an antenna (that contain receptors that allow cell to detect signals about its immediate environment)
24
Q

What is the structure of cilia?

A

-protrusions from the cell surrounded by the cell surface membrane
- each contain microtubules
-they are formed from centrioles

25
What is the function of a vacuole?
-only in plant cells -filled with water and solutes and maintains cell stability because when full it pushes against cell wall making it turgid -if all plant cells are turgid it helps support plant especially in non-woody plants
26
What is the structure of a vacuole?
-surrounded by a membrane called tonoplast and contains fluid
27
What is the magnification formula?
I=AM
28
List 4 ways that prokaryotic cells are similar to eukaryotic cells
Prokaryotic cells (e.g. bacteria ) are similar to eukaryotic cells in that they have : .a plasma membrane .cytoplasm .ribosomes for assembling amino acids into proteins .DNA and RNA
29
How are prokaryotic cells different from eukaryotic cells?
.they are much smaller .have a less well developed cytoskeleton with no centrioles .do not have a nucleus .do not have membrane bound organelles e.g. mitochondria, endoplasmic reticulum,Golgi apparatus .have a cell wall that is made of petidoglycan not cellulose .have smaller ribosomes .have naked DNA that is not wound around histone proteins but floats free in cytoplasm as a loop(not linear chromosomes)
30
List some other features of prokaryotic cells
.they have a protective waxy (slime) capsule surrounding their cell wall .some have small loops of DNA called plasmids(contain essential genes) as well as the main large loop of DNA .they have pili-small hair like projections that enable bacteria to adhere to host cells or each other and allow the passage of plasmid DNA from one cell to another .flagella-the structure of these flagella differ from that of the eukaryotic undulipodia
31
Describe the endosymbiont theory and the evidence behind it
A theory as to how eukaryotic cells arose from prokaryotic cells.As from fossil evidence, both chloroplasts and mitochondria share characteristics with prokaryotic cells. They: .have small ribosomes .have loops of DNA .also contain RNA .can divide by binary fission
32
What are the 4 main functions of the cytoskeleton
1.provides mechanical strength to cells 2.aids transport within cells 3.enables cell movement 4.keeps the cell’s shape stable
33
What is the cytoskeleton?
A network of protein structures within the cytoplasm.
34
How does the cytoskeleton provide mechanical strength to cells?
The protein microfilaments within the cytoplasm give support and mechanical strength, they keep the cell’s shape stable and allow cell movement . Microtubules also provide shape and support to cells
35
How does the cytoskeleton aid transport within cells?
Microtubules help substances and organelles to move through the cytoplasm within a cell. .They form the track along which motor proteins (dynein, kinesin and myosin)walk and drag organelles from one part of the cell to another .During mitosis chromosomes are moved along the microtubules of a spindle .Microtubules also make up the cilia,undulipodia and centrioles
36
What do intermediate filaments in the cytoskeleton do?
Intermediate filaments are made of a variety of proteins. They : .anchor the nucleus within the cytoplasm .extend between cells in some tissues,between special junctions,enable cell to cell signalling and allowing cells to adhere (stick to ) a basement membrane(cytoskeleton under cell membrane )therefore stabilising tissues
37
Why is staining used?
-coloured stains bind to chemicals on or in the specimen which allows the specimen to become visible e.g.to see certain (named e.g nucleus) organelles -improves contrast
38
What is differential staining?
a technique which involves many chemical stains being used to stain different parts of a cell in different colours.
39
Light (optical) microscopes
-use light to form an image -poor resolution due to lights long wavelength -can be used to observe eukaryotic cells, their nuclei and possibly mitochondria and chloroplasts -cannot be used to observe smaller organelles .e.g. ribosomes ,ER or lysosomes
40
Transmission electron microscope (TEM)
-use electromagnets to focus a beam of electrons. Beams of electrons transmitted through specimen -denser parts absorb more electrons makes denser parts appear darker -produces 2D black and white detailed image (electron micrograph )
41
Advantages of transmission electron microscope (TEM)
-high resolution images ,high magnification -internal structures within cells and even organelles can be seen (since high resolution)
42
Describe what happens during protein synthesis
TRANSCRIPTION 1.in the nucleus a copy of a section of DNA is made which is called mRNA. 2.mRNA leaves nucleus through nuclear pore TRANSLATION 3.mRNA attaches to a ribosome the instructions for the protein is translated and protein molecules are assembled 4.protein is transported through the cisternae of the RER 5.vesicles with protein inside are pinched off from RER and pass via microtubules and motor proteins, to the Golgi apparatus 6.vesicles fuse with Golgi apparatus where the protein molecules may be modified for release 7.the proteins are released through exocytosis
43
What does the cytoskeleton consist of?
It consists of: .rod-like microfilaments made up of subunits of the protein actin, they are polymers of actin and each microfilament is about 7nm in diameter .intermediate filaments about 10nm in diameter .straight ,cylindrical microtubules made of protein subunits called Tubulidentata about 18-30nm in diameter
44
What is the magnification and resolution of a light microscope ?
Magnification = x1500 Resolution = 200nm
45
What is the magnification and resolution of a transmission electron microscope?
Magnification = x500000 Resolution = 0.2nm
46
What is the magnification and resolution of a scanning electron microscope ?
Magnification = x100000 Resolution =0.2nm
47
Define magnification
-the number of times larger an image appears compared with the size of the object
48
Define resolution
-a measure of the microscope’s ability to distinguish between two separate points
49
Name two structures present in animal cells but not plant cells
Centriole Lysosomes
50
How do you convert from centimetre (cm) to millimetre (mm) to micrometre (μm) to nanometre(nm)?
-cm x10 = mm -mm x 1000= μm -μm x 1000= nm
51
D
52
A light microscope can be used to observe yeast cells. State the equipment that would be needed, in addition to a microscope, to measure the average diameter of yeast cells (2 marks)
-eyepiece graticule -STAGE micrometer

Biology (19 decks)

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