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cells - bio alevel > chapter 3 - cell structure > Flashcards

chapter 3 - cell structure Flashcards

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1
Q

What are the two types of cells

A

Eukaryotic and prokaryotic

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2
Q

What are the organelles present in eukaryotic cells?

A

Nucleus, ribosomes, mitochondria, rough endoplasmic reticulum, smooth endoplasmic reticulum, lysosome, Golgi apparatus, chloroplasts, cytoplasm, cell membrane, cell wall and vacuoles

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3
Q

What is the nucleus made of

A

Nuclear envelope, nuclear pores, nucleoplasm, chromatin and nucleolus.

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4
Q

What is the structure and function of the nuclear envelope

A

Structure:
A double membrane phospholipid layer that surrounds the nucleus ( the outer membrane is continuous with the endoplasmic reticulum
Function:
-Controls entry + exit of materials (ions , molecules, rna) into nucleus
-contains the reaction taking place in it

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5
Q

What is the structure and function of the nuclear pores?

A

Structure:
-pores in the nuclear envelope membrane
Function:
-allow large molecules, like mRNA out of the nucleus

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6
Q

What is the structure and function of the nucleoplasm?

A

Structure:
-granular, jelly-like material
Function:
-contains nucleotides and enzymes to make RNA

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7
Q

What is the structure and function of chromatin?

A

Structure:
DNA bound around histones = chromosomes
Function :
To be DNA

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8
Q

What is the structure and function of the nucleolus?

A

Structure:
-small, spherical feature in nucleoplasm
Function:
-manufactures rRNA and assembles ribosomes subunits

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9
Q

What is the structure of ribosomes?

A

-small granules in the cytoplasm or on RER
2 types:
-80s - in eukaryotic cells, diameter = 25nm
-70s - in prokaryotic cells, mitochondria + chloroplasts slightly smaller
2 subunits - 1 small, 1 large , each have rRNA and protein

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10
Q

What is the function of ribosomes?

A

The site of protein synthesis

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11
Q

What is the structure of the mitochondria

A

-double phospholipid membrane
-cristae = extensions of inner membrane , provides large surface area for enzyme attachment
- matrix = fluid of mitochondria, contains ribosomes, proteins, and enzymes ( for Krebs cycle)
-mitochondrial loop of DNA = has genes of some enzymes in aerobic respiration.

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12
Q

What is the function of mitochondria?

A

The site of aerobic respiration and releases ATP

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13
Q

What is the structure of the rough endoplasmic reticulum?

A
  • interconnected membranous sacs and tubules with ribosomes on its outer surface
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14
Q

What is the function of the rough endoplasmic reticulum?

A

-provides a large surface area for protein and glycoproteins synthesis and modifying proteins
-provides pathway in to Golgi apparatus for protein transport

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15
Q

What is the structure of the smooth endoplasmic reticulum?

A
  • smooth interconnected membranous sac and tubules. NO ribosomes
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16
Q

What is the function of the smooth endoplasmic reticulum?

A
  • for lipid synthesis, storage and transportation, toxin modification and glycogenesis ( turning glycogen into glucose )
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17
Q

What is the structure of a lysosome ?

A
  • a small membranous vesicle
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18
Q

What is the function of a lysosome?

A

-they have lysozymes which break down certain bacteria and dead cells
- hydrolyse material digested be phagocytic cells
- release enzymes outside of cell to destroy material
- digest worm out cells so the chemicals can be reused

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19
Q

What is the structure of the Golgi apparatus?

A
  • flattened sacs called cisternae with vesicles that fuse with them
  • the vesicles fuse with the ERs
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20
Q

What is the function of the Golgi apparatus?

A

-proteins and lipids re emptied into it from the ERs
-these modified, packaged ( sorted ) and transported to target cells
-specifically they form glycoproteins ( carb + proteins)
- secrete carbohydrates like cellulose
-produce secretory enzymes

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21
Q

What is the structure of the cell membrane ?

A
  • a phospholipid bilayer, tails on the inside, heads on the outside
  • has proteins, cholesterol and carbs embedded in it
    -proteins can act as receptors
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22
Q

What is the function of a cell membrane ?

A
  • to control the exit and entry of molecules
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23
Q

What is the structure of the cytoplasm ?

A
  • gel like structure
    -70% water has proteins, sugars, ions and fatty acids
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24
Q

What is the function of the cytoplasm?

A

-site of chemical/ metabolic reactions

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25
What is the structure of the cell wall?
- plant cells = made of microfibrils of cellulose - fungi cells = made of chitin - prokaryotes = made of murein
26
What is the function of the cell wall ?
-provide structural strength to cell = prevent from bursting due to osmosis
27
What is the structure of chloroplasts ?
- has a nuclear envelope which has a double membrane - has grana = stacks of disk like structures called thylakoids , thylakoids have chlorophyll - has stroma = fluid filled matrix with enzymes for photosynthesis
28
What is the function of chlorplasts?
- absorbs light energy for photosynthesis
29
What is the structure of a vacuole?
- sac filled with cell sap -surrounded by single membrane called tonoplast
30
What is the function of the vacuole ?
- to keep the cell turgid - when it contains more water, it pushes against the cell wall, the pressure makes sure plant does not wilt - also can temporarily store sugars and amino acids - pigment of it may colour petals to attract pollinators
31
What is the structure of the slime capsule
-layer of slime around prokaryotic cells
32
What is the function of the slime capsule?
- protects cell from immune system - allows cell to attach to surface in its environment
33
How is DNA structured in prokaryotic cells?
- naked in cytoplasm with no bound proteins - has no non coding parts and is a single loops
34
What is the structure and function of a plasmid?
-small circular section of DNA in cytoplasm - often have useful genes like antibiotic resistance -can be shared between other bacteria using pili
35
What is fimbriae
-structures used by bacteria to attach to host cells
36
What is flagella
- tails on some prokaryotic cells used for movement
37
What do viruses have?
- capsid, attachment protein, genetic material = in every virus - enzyme, liquid envelope , matrix
38
What does the attachment protein of a virus do ?
Attach to receptors on host cell membranes
39
What is the function of a capsid in a virus?
- for protecting genetic material
40
What is the function of the genetic material in viruses?
- codes for viral proteins
41
What are the three types of microscopes
, optical microscope, TEM microsome and SEM microscope
42
Which microscope has the highest magnification and resolution?
TEM microscope
43
Which microscopes show in 3D and which in 2D
- 2D = TEM and optical - 3D = SEM
44
Which microscopes have real images and which virtual images
- real = optical - virtual = TEM and SEM
45
What are the benefits and limitations of the electron microscopes?
benefits : - images in 3D for SEM - high magnification and resolution limitations : - specimen must be dead as its in a vacuum - expensive - hard to move - specimen are difficult to prepare
46
What are the benefits and limitations of optical microscopes ?
benefits : - cheap - easy to move - specimen is alive - easy to prepare specimen limitations : - low resolution - low magnification
47
How do we measure cells using an eyepiece graticule?
1- fit an eyepiece graticule into the eyepiece of a microscope = a numbered scale 2- place a stage micrometer on the stage and focus on it with an objective lens 3- move the stage so the scales on the graticule and the stage micrometer are lined up 4- lets say each division in the stage micrometer is 100 micrometers , count how many lines of the graticule can fit into one division and record this number 5 - then do 100 divided by this number to work out how many micrometers each division on the graciticule is used for 6- now the graticule can be used to measure cells.
48
What is cell fractionation?
Breaking up cells so scientist can study the individual organelles
49
What are the 2 steps of cell fractionation?
Homogenisation and Ultaracentrifugation
50
What is the process of homogenisation ?
Blending the cells in a solution and filtering the solution so only the organelles are left
51
What conditions must the solution have during homogenation ?
- ice cold - when the cell is broken up, enzymes may be released that damage organelles - isotonic - same water potential so organelles don’t shrivel or burst from osmosis - pH buffer solution - to make sure pH doesn’t damage organelles ( proteins )
52
What is the process of ultracentrifugation?
- separating organelles so they can be studied 1 - the filtrate is put into a centrifuge and spun at a low speed 2 - the heaviest organelle sinks to the bottom and forms a pellet , this is then filtered out. 3 - the remaining supernatant ( liquid ) is spun again at a higher speed 4 - the next heaviest organelles is forms a pellet 5 - then repeat
53
What is the order in which organelles are separated in ultracentrifugation?
Biggest to smallest : - nucleus - chloroplasts - mitochondria - lysosomes - endoplasmic reticulum - ribosomes
54
What are the stages of the cell cycle ?
- G1 - growth 1 - S - DNA synthesis - G2 - growth 2 - mitosis - G1 , S and G2 = interphase
55
What are the 4 stages of mitosis ?
- prophase , metaphase , anaphase and telophase
56
What happens in prophase ?
- the chromosomes condense and become visible - the centrioles ( which create spindle fibres ) separate and move to opposite sides of the cell
57
What happens in metaphase ?
- the chromosome line up in the middle of the cell - the spindles fibres connect to the centromeres of the chromatids
58
What happens in anaphase ?
- the spindle birds retract and pull the chromosomes apart at the centromeres - they divide it to sister chromatids - this stage needs ATP which is provided by respiration.
59
What happens in telophase ?
- the chromosomes at each pole becomes longer and thinner again ( so they are no longer visible ) - spindle fibres disintegrate and the nucleus starts to reform - the final stage is cytokinesis whee the cytoplasm splits in two to form two genetically identical daughter cells .
60
What is the formula for mitotic index ?
- number of cells in mitosis / the total number of cells x 100
61
What do prokaryotic cells use to divide ?
Binary fission
62
What is the process of binary fission involve ?
- the circular DNA and the plasmids replicate - the cytoplasm divides and produces two daughter cells, each with one circular DNA and a variable number of plasmids
63
How do viruses divide ?
- they don’t as they are not living - instead , they inject the host cells with their nucleic acid and the host cell replicates the viruses
64
What causes cancer ?
- uncontrolled cell division which leads to tumours

cells - bio alevel (3 decks)

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