Biology A Level > Cell Structure > Flashcards

Cell Structure Flashcards

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1
Q

What is the function of flagella?

A

Allow cells to move, eukaryotic flagella have a 9+2 structure and are called undulipodia, prokaryotic flagella don’t have the 9+2 arrangement
- The 9+2 arrangement is also the arrangement in cilia

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2
Q

What is the function of a slime capsule?

A

Provides an extra layer to protect the cell and helps it stick to surfaces

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3
Q

What is the function of a plasma membrane?

A

To regulate the passage of molecules in and out of the cytoplasm

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4
Q

What is the function of pili?

A

Pili are small hairlike projections found on bacteria that allow the bacteria to adhere to host cells or each other allowing the passage of plasmid DNA from one cell to another

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5
Q

What is the function of ribosomes?

A

To synthesise proteins

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6
Q

What is a DNA plasmid?

A

Loops of DNA that can be shared between cells that often carry immunities

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7
Q

What is nucleoid DNA?

A

The prokaryotic equivalent of a nucleus

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8
Q

What is the Golgi body and what is its function?

A

A membrane bound organelle that is made up of membrane bound sacs. Its function is to process and bundle lipids as they are synthesised in the cell. The Golgi body also modifies and packages proteins

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9
Q

What is the function of the rough ER?

A

Rough ER is studded with many ribosomes that are essential for the process of protein synthesis. The rough ER is also essential for the transportation of proteins to the Golgi body

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10
Q

What is the function of the smooth ER?

A

The smooth Er acts as a storage organelle, it’s also important in the creation and storage of lipids and steroids

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11
Q

What are the functions of the cytoskeleton?

A

Structure, motion, transport and chromosome division

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12
Q

What proteins make up the cytoskeleton?

A

Thick microtubules, thin microfilaments, intermediate filaments

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13
Q

How are objects moved along the cytoskeleton?

A

Microtubule motor proteins move up and down the cytoskeleton carrying vesicles full of other proteins to different areas of the cell, or for transport out of the cell (kinesin carries the the vesicle along the microtubule motor protein)

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14
Q

How do flagella move?

A

Flagella move in a wave or whip-like motion, eukaryotic flagella depend on ATP for energy

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15
Q

How do cilia move?

A

Cilia move in a rowing motion, they are driven by motor proteins

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16
Q

Describe the process of a protein being made and secreted

A
  • The gene that has the coded instructions for a protein is transcribed into a length of mRNA
  • Many copies of this mRNA are made and they pass out of the nuclear pores to the ribosomes
  • Ribosomes translate the mRNA and produce the protein
  • The protein travels through the rough ER and is packaged into a vesicle so it can travel to the Golgi body
  • The Golgi body modifies the protein (usually by adding carbohydrate chains)
  • The processed proteins are then packaged into vesicles and travel to the plasma membranes
  • The membrane of the vesicle is made of the same phospholipids as the plasma membranes
  • The vesicle fuses with the plasma membrane and the protein contents are released outside of the cell by exocytosis
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17
Q

What is the function of the mitochondria?

A
  • Site of ATP production during aerobic respiration
  • They are self replicating so if the cell needs more energy, more can be made
  • They are abundant in cells where much metabolic activity takes place
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18
Q

What is the function of a chloroplast?

A
  • Site of photosynthesis

- Chlorophyll that is contained in chloroplasts traps light energy which helps to make ATP

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19
Q

What is the function of a lysosme?

A
  • Contains digestive enzymes and separates enzymes from the rest of the cell
  • The digestive enzymes are used to digest worn out organelles, engulfed viruses or bacteria and food particles
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20
Q

What is the function of the vacuole?

A
  • Mainly used for storage

- Help to keep cell rigid

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21
Q

What is the function of the cell wall?

A
  • To support the cell
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22
Q

What is the function of cilia?

A
  • To move mucus that contains trapped molecules such as dust
  • Nearly all cells in the body have one cilium that acts as an antenna that contains receptors and allows the cell to detect signals about its immediate environment
  • Help cells move by moving in a rowing motion driven by motor proteins
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23
Q

What is the function of undulipodia?

A
  • Enables spermatozoon to move

- Enables cells to move

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24
Q

What is the function of a centriole?

A
  • They form spindle fibres that separate chromosomes during cell division
  • Assist in the formation of cilia and undulipodia
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25
How are centrioles involved in the production of cilia and undulipodia?
- Before cilia form, the centrioles multiply and line up beneath the plasma membrane - Microtubules then sprout outwards from each centriole, forming either cilia or undulipodia - The first component of cilium to be formed is the basal body which is identical in structure to a centriole
26
What is resolution?
The shortest distance between two points on a specimen that can be distinguished by the observer as separate entities
27
What is the equation for magnification?
- Image size / actual size | - Magnification means how many times bigger an image is than the actual size
28
What is the equation for the length of one eyepiece division?
- 1 epu = length of stage micrometer (um) / number of epu taken to make up the stage micrometer - If the stage micrometer is 4 times bigger than the eyepiece graticule and the stage micrometer is 1000um then the length of one epu is 1000/400 because the eyepiece graticule has 100 divisions. 100 x 4 = 400 - Each division of the stage micrometer is equal to 10um and the stage micrometer has 100 divisions so therefore the length of the stage micrometer is 1mm or 1000um
29
What is active transport?
- Active transport is a process used to move substances against their concentration gradient - Active transport needs more energy than just the kinetic energy if the molecules, this energy is provided by the hydrolysis of ATP - Cells may need to accumulate more of a particular ion than they would be able to by simple or facilitated diffusion alone - Requires a carrier protein
30
What are the main functions of carrier proteins?
- They have a region which enables them to combine reversibly with certain solute molecules or ions - They have a region that enables them to act as enzymes when this region of the carrier protein binds to a molecule of ATP and allows the hydrolysis of this molecule - The energy from ATP helps the carrier protein change its conformation (shape) and in doing so, it carries the ion from one side of the cell to the other
31
What is bulk transport?
- Some cells need to transport large molecules and particles that are too large to pass through the plasma membrane - Requires ATP - They do this by bulk transport, there are two main types of bulk transport: endocytosis and exocytosis
32
What is endocytosis?
- Endocytosis is the process that allows large particles to be brought into a cell (they don't pass through the plasma membrane) - Instead a segment of the plasma membrane surrounds and encloses the molecule into a vesicle, it can now be brought into the cell - ATP is required as it's an active process
33
What is phagocytosis?
Phagocytosis is when solid matter is ingested by a cell
34
What is pinocytosis?
When cells ingest liquid matter
35
What is exocytosis?
- Exocytosis is the process that allows large molecules to be exported out of cells - A secretory vesicle containing the large molecule is moved towards the plasma membrane and it fuses with the plasma membrane, the contents of the vesicle is then released outside of the cell - ATP is needed to fuse the membranes together as well as for moving the vesicles
36
What is a cell?
The smallest single unit of life
37
What is a tissue?
A group of similar cells carrying out a specific function
38
What is an organ?
A collection of tissues that work together to carry out a specific function
39
What are the 4 types of animal tissue?
- Epithelial - Connective - Muscle - Nervous
40
What are the 3 types of plant tissue?
- Epidermal - Vascular - Meristematic
41
What is magnification?
The number of times larger an image appears compared with the size of the object
42
What are the advantages of using optical microscopes?
- Relatively cheap - Easy to use - Portable - Able to be used to study whole living specimens
43
Do optical microscopes use visible light?
Yes, they use visible light which has a wavelength of between 400 and 700nm
44
What do objects that are closer than 200nm together appear as when observed under a light microscope?
They appear to be one object as the beam of light produced by the light microscopes can't fit between the two objects
45
What does the rack stop do on a microscope?
It stops the stage and microscope slide from getting too close to the objective lenses
46
What is a photomicrograph?
A photograph of an image seen using an optical microscope
47
What is an electron micrograph?
A photograph of an image seen using an electron micrograph
48
What are organelles?
Small structures inside cells each of which have a speciic function
49
What are laser scanning microscopes?
- Microscopes that use laser light to scan an object and assemble the pixel information into one image on a computer screen - The images are high resolution - These images have depth selectivity so you can focus on structures at different depths
50
What are confocal microscopes used for?
They are used in the medical profession and also in many branches of biological research
51
What is an electron microscope?
- An electron microscope uses a beam of fast travelling electrons with a wavelength of about 0.004nm meaning that electron microscopes have a much greater resolution than optical microscopes - Electrons are fired from a cathode and focused by magnets onto a screen or photographic plate
52
What are stains?
Stains are coloured chemicals that bind to molecules in or on the specimen, making the specimen easy to see
53
What does acetic orcein do?
Binds to DNA and stains chromosomes dark red
54
What is methylene blue?
An all purpose stain
55
What does eosin stain?
Cytoplasm
56
What does Sudan red stain?
Lipids
57
What does iodine in potassium iodide solution stain?
It stains cellulose in plant cell walls yellow and stains starch granules blue/black
58
How are slides of specimens prepared?
- The specimens are dehydrated - They are then embedded in wax to prevent distortion during slicing - A special instrument is used to make very thin slices called sections, these are stained and mounted in a special chemical to preserve them
59
What is the function of the nucleus?
Contains the cell's DNA
60
What is the function of the nucleolus?
Makes RNA and ribosomes
61
What is the function of the nuclear envelope?
Surrounds the nucleus
62
What is kinesin?
Kinesin is a protein that carries vesicles along a microtubule motor protein
63
How do cells move?
In eukaryotic cells, some microtubules extend out from the centrioles that have lined up beneath the plasma membrane. They form flagella (undulipodia) or cilia. Both of these structures are made out of nine pairs of fused microtubules arranged into a circle with 2 central unfused microtubules
64
Why do lipid tails repel polar molecules?
They are non-polar which means they're hydrophobic (water is polar and polar and non-polar molecules repel each other)
65
What adaptations do certain types of prokaryotic cells have?
- A protective waxy capsule surrounding their cell wall - Small loops of DNA called plasmids, as well as the large loop of DNA - Pili, which are hair-like projections that enable bacterial cells to adhere to host cells or one another, allowing the passage for plasmid DNA from one cell to another - Flagella, long whip-like projections that enable the prokaryotic cells to move, the structure of these flagella is different to that of a eukaryotic undulipodia
66
How are prokaryotic cells similar to eukaryotic cells?
- They both have a plasma membrane - They both have a cytoplasm - They both have ribosomes for assembling amino acids into proteins - They both have DNA and RNA
67
How are prokaryotic cells different to eukaryotic cells?
- Prokaryotic cells are much smaller - Prokaryotic cells have a much less well-developed cytoskeleton with no centrioles - No nucleus - No membrane bound organelles such as, Golgi body, endoplasmic reticulum, lysosomes, mitochondria, chloroplasts - Have a peptidoglycan cell wall and not a cellulose cell wall
Biology A Level
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