Biology > B5 And B6 > Flashcards

B5 And B6 Flashcards

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1
Q

What’s the structure of the nucleus?

A

Nuclear envelope: double membrane
Nuclear pores
Nucleoplasm: granular, jelly like material
Chromosomes: protein bound linear DNA
Nucleolus: small sphere which is the site of RNA production and makes ribosomes

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2
Q

What is the function of the nucleus

A

Site of DNA replication and transcription (making mRNA)
Contains the genetic code for each cell

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3
Q

What is the structure of mitochondria

A

Double membrane
Inner membrane called the cisternea
Fluid filled centre called the mitochondrial matrix
Loops of mitochondrial DNA
70s ribosomes

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4
Q

What is the function of the mitochondria

A

Site of aerobic respiration
Site of ATP production
DNA to code for enzymes needed in respiration

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5
Q

What is the structure of mitochondria

A

Double membrane
Inner membrane called the cisternea
Fluid filled centre called the mitochondrial matrix
Loops of mitochondrial DNA
70S ribosomes

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6
Q

What is the function of mitochondria

A

site of aerobic respiration
Site of ATP production
DNA to code for enzymes needed in respiration

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7
Q

What is the structure of chloroplasts

A

Surrounded by a double membrane
Contains thylakoids (folded membranes embedded with pigment)
Fluid filled stromata contains enzymes for photosynthesis
Found in plants

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8
Q

What is the function of chloroplasts

A

Site of photosynthesis

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9
Q

What is the structure of Golgi apparatus and vesicles

A

folded membranes making cisternea
Secretary vesicles pinch off from the cisternea

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10
Q

What is the function of Golgi apparatus and Golgi vesicles

A

Add carbohydrates to proteins to form glycoproteins
• Produce secretory enzymes
• Secrete carbohydrates
• Transport, modify and store lipids
• Form lysosomes
Molecules are ‘labelled’ with their destination
• Finished products are transported to cell surface in Golgi vesicles where they fuse with the membrane and the contents are released.

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11
Q

What is the structure of lysosomes

A

Bags of digestive enzymes: contain 50 different enzymes

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12
Q

What is the function of lysosomes

A

Hydrolyse pathogens in phagosomes
Completely break down dead cells (autolysis)
Exocytosis: release enzymes to outside of cell to destroy material
Digest worn out organelles for reuse of materials

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13
Q

What is the structure of ribosomes

A

small made up of two sub units of proteins and rRNA
80s- large ribosomes found In eukaryotic cells
70s- smaller ribosomes found in prokaryotic cells, mitochondria and chloroplasts

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14
Q

What is the function of ribosomes

A

Site of protein synthesis

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15
Q

What is the structure of rough and smooth endoplasmic reticulum

A

rough and smooth endoplasmic reticulum both have folded membranes called cisternea
Rough have ribosomes on their cisternae

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16
Q

What is the function of SER and RER

A

RER: protein synthesis
SER: synthesis and stores lipids and carbohydrates

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17
Q

What is the structure of cell wall

A

in plants and fungi cells
Plants: made of microfibrils of the cellulose polymer
Fungi: made of chitin, a nitrogen containing polysaccharide

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18
Q

What is the function of the cell wall

A

provide structural strength to the plant/fungal cell

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19
Q

What is the structure of the cell vacuole

A

Filled with fluid and surrounded by a single membrane called the tonoplast

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20
Q

What is the function of the cell vacuole

A

make cells turgid and therefore provide supports
Temporary storage of sugar and amino acids
The pigments may colour petals to attract pollinators

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21
Q

What is the structure of the plasma membrane

A

found in all cells
Phospholipid bilayer- molecules embedded within and attached on the outside
(Proteins, carbohydrates, cholesterol)

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22
Q

What is the function of the plasma membrane

A

Controls the entry and exit of molecules

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23
Q

List the differences between prokaryotes and eukaryotes

A

prokaryotic cells are much smaller than eukaryotic

prokaryotes have no membrane bound organelles, smaller ribosomes (70S), no nucleus (single circular DNA molecule in cytoplasm instead), a cell wall made of murein a glycoprotein

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24
Q

What structures are found in prokaryotic cells that are not in eukaryotic cells?

A

One or more plasmids
A capsule around the cell
One or more flagella

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25
What structures are found in viruses?
Genetic material: Genetic material codes for (viral) protein Capsid: A protein shell that protects the genetic material/RNA/DNA Attachment proteins: Attached proteins bind to receptors on host cell being infected
26
Why are viruses considered non-living and acellular?
Non living: No metabolic reactions, cannot move, respire, replicate and no nutrition acellular: not made up of cells, no cell membranes
27
Define magnification
The magnification of a microscope refers to how many times larger the image is compared to the object.
28
Define resolution
The resolution of a microscope is the minimum distant between two objects in which they can still be viewed as separate. The resolution in an optical microscope is determined by the wavelength of light, and the wavelength of the beam of electrons determines the resolution in an electron microscope.
29
Compare optical microscopes and electron microscopes (scanning and transmission). Include magnification, resolution, and sample preparation.
Transmission Electron Microscopes(TEM) Extremely thin specimens are stained and placed in a vacuum. An electron gun produces a beam of electrons that pass through the specimen. Some parts absorb the electrons and appear dark. The image produced is 2D and shows detailed images on the internal structure of cells. Scanning Electron Microscope (SEM) The specimens do not need to be thin, as the electrons are not transmitting through. Instead, the electrons are beamed onto the surface and the electrons are scattered in different way: depending on the contours. This produces a 3D image.
30
What is the source used to produce an image in an optical microscope?
A beam of light is condensed to create the image.
31
What is the source used to produce an image in an electron microscope?
A beam of electrons is condensed to create the image, and electromagnets are used to focus the beam.
32
Why does an optical microscope have poorer resolution?
Because light has a longer wavelength
33
Why does an electron microscope have higher resolution?
Because electrons have a much shorter wavelength, giving a higher resolving power
34
What is the magnification like in an optical microscope?
It has a lower magnification
35
What is the magnification like in an electron microscope?
It has a much higher magnification.
36
Can you view living samples using an optical microscope?
Yes, you can view living samples
37
Can you view living samples using an electron microscope
No, the sample must be placed in a vacuum, so it must be non-living
38
Do optical microscopes produce colour images?
Yes, they can produce colour images
39
Do electron microscopes produce colour images?
No, they produce black and white images.
40
What are the two steps for cell fractionation and explain why the solution must be cold, isotonic and buffered
Homogenisation: The cells must be broken up (homogenised) using a blender. The cells are blended in a cold, isotonic and buffered solution The solution is filtered to remove large cell debris Ultracentrifugation: The filtered solution is spun at different speeds in a centrifuge Organelles are separated according to their densities Cells are broken open to release the contents and organelles are then separated The cells must be prepared in a cold, isotonic and buffered solution: Cold: to reduce enzyme activity. When the cells break open enzymes are released which could damage the organelles Isotonic: must be the same water potential to prevent osmosis as this could cause the organelles to shrivel or burst Buffered: the solution has a pH buffer to prevent damage to organelles
41
List the order of organelle separation based on density.
1. Nucleus 2. Chloroplasts (if using plant tissue) 3. Mitochondria 4. Lysosomes 5. Endoplasmic reticulum 6. Ribosomes
42
Does simple diffusion require energy
No, it does not require energy
43
44
In which direction do molecules move in simple diffusion
From a higher concentration to a lower concentration
45
What types of molecules move by simple diffusion
Small, lipid-soluble molecules
46
Does facilitated diffusion require energy
No, it does not require energy
47
In which direction do molecules move in facilitated diffusion?
From high concentration to low concentration.
48
What types of molecules move by facilitated diffusion?
Ions and polar molecules that cannot pass directly through the membrane
49
Does osmosis require energy?
No, it does not require energy
50
In which direction does water move during osmosis?
From a region of higher water potential to a region of lower water potential.
51
What type of molecule is transported by osmosis
Water
52
Does active transport require energy?
Yes, it requires energy (ATP)
53
In which direction do substances move in active transport?
From a low concentration to a high concentration (against the gradient)
54
What types of molecules are moved by active transport?
Typically ions.
55
What is water potential?
Water potential (Ψ) is the pressure created by water molecules, and it determines the direction of water movement. Pure water has the highest water potential (0 kPa), and adding solute makes water potential more negative.
56
What is an isotonic solution?
A solution with the same water potential as the cell.
57
What is the direction of osmosis in an isotonic solution?
There is no net movement of water into or out of the cell.
58
What is a hypotonic solution?
A solution with a higher water potential than the cell (less negative)
59
What is the direction of osmosis in a hypotonic solution?
Water moves into the cell.
60
What is a hypertonic solution?
A solution with a lower water potential than the cell (more negative).
61
What is the direction of osmosis in a hypertonic solution?
Water moves out of the cell
62
Describe the process of co-transport of glucose and sodium ions in the ileum. Include all stages.
Sodium ions are actively transported out of the epithelial cell into the blood This reduces the sodium ion concentration in the epithelial cell Sodium ions can then diffuse from the lumen down their concentration gradient into the epithelial cells The protein the sodium ions diffuse through is a co-transporter protein so either glucose or amino acids also attach and are transported into the epithelial cell against their concentration gradient
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