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BIOLOGY A LEVEL > TOPIC 2 - A: cell structure and division > Flashcards

TOPIC 2 - A: cell structure and division Flashcards

(57 cards)

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1
Q

Function of cell-membrane

A

Regulates movement of substances into and out of cell. It also has receptor molecules on it which allows it to respond to chemical like hormones

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2
Q

Function of the nucleus

A

Controls the cells activities. DNA contains instructions to make proteins. Nuclear pores allow substances to move between the nucleus and cytoplasm. Nucleolus makes ribosomes.

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3
Q

Function of mitochondrion

A

Site of aerobic respiration which produces ATP - a common energy source in the cell

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4
Q

Structure of a mitochondrion

A

Mitochondria are enclosed by two membranes—a smooth outer membrane and a markedly folded or tubular inner mitochondrial membrane, which has a large surface and encloses the matrix space. The folds of the inner membrane are known as cristae, and tube-like protrusions are called tubules

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5
Q

Function of a chloroplast

A

Site where photosynthesis takes place - some parts of photosynthesis happen in the grana, some parts in the stroma

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6
Q

Structure of a chloroplast

A

Chloroplasts have their own DNA, ribosomes and have inner and outer membranes. The space enclosed by the inner membrane contains a set of interconnected and stacked fluid-filled membrane sacs called thylakoids. Each stack of thylakoids is called a granum

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7
Q

Function of golgi apparatus

A

Processes and packages new lipids and proteins - also makes lysosomes

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8
Q

Function of golgi vesicle

A

Stores lipids and proteins made in golgi apparatus and transports them out of the cell

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9
Q

Function of lysosomes

A

Contains hydrolytic enzymes. They are kept separate from the cytoplasm by surrounding the membrane, and can be used for digesting and invading cells or to break down worn out components of the cell

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10
Q

Function of ribosomes

A

Site of protein synthesis

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11
Q

Function of rough endoplasmic reticulum

A

Folds and processes proteins that have been made at the ribosomes

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12
Q

Function of smooth endoplasmic reticulum

A

Synthesises and packages lipids

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13
Q

Function of cell wall

A

Supports cells and prevents them from changing shape

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14
Q

Function of cell vacuole

A

Helps maintain pressure inside the cell and keeps the cell rigid - stops plant from wilting

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15
Q

Where is murein used in prokaryotic cells?

A

In the cell wall

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16
Q

Name and describe the process by which prokaryotic cells reproduce

A

Binary fission:
- the circular DNA and plasmids replicate
- the main DNA loop is only replicated once but the plasmids can be replicated several times
- the cell gets bigger and the DNA loops move to opposite poles of the cell
- cytoplasm divides and new cell walls begin to form
- cytoplasm divides and two daughter cells are produced with one copy of circular DNA but variable number of plasmids

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17
Q

What is a capsid?

A

The protein coat that surrounds the core of genetic material in a virus

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18
Q

What is the role of attachment proteins?

A

They allow a virus to attach to specific host cells, which have the complementary receptor proteins

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19
Q

What is the difference between magnification of a microscope and its resolution?

A

Magnification is how much bigger the image is than the specimen. Resolution is how well a microscope can distinguish between 2 points that are close together

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20
Q

What type of microscope would study lysosomes?

A

Electron microscope

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21
Q

How do transmission microscopes work?

A

TEM uses electromagnets to focus a beam of electrons, which is then transmitted through the specimen. Denser parts of the specimen absorb more electrons, which makes them look darker on the image you end up with

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22
Q

How do scanning electron microscopes work?

A

SEM scans a beam of electrons across a specimen. This knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image

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23
Q

One advantage and disadvantage of TEMs

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A

Advantage - gives high resolution images, so can be used to look at small objects
Disadvantage - can only be used on non-living specimens, only used on thin specimens

24
Q

What is a temporary mount microscope slide?

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A

A prepared microscope slide in which the specimen had been suspended in a drop of liquid

25
What is a microscope artefact?
Something you can see down the microscope that isn't a part of the cell or specimen you are looking at
26
Give the two ways in which homogenisation for cell fractionation is done
Vibrating cells or grinding them up in a blender
27
Describe what happens at the filtration step of cell fractionation and explain why its carries out
The homogenised solution is filtered through a gauze to separate any large cell debris or tissue debris, like connective tissues
28
What is the cell cycle?
The process that all body cells from multicellular organisms use to grow and divide
29
Why is mitosis needed?
Growth and repairing damaged tissues
30
In what stage of the cell cycle does all the DNA unravel
Interphase
31
Describe what happens during prophase
The chromosomes condense, getting shorter and fatter. The centrioles start moving to opposite ends of the cell, forming the spindle. The nuclear envelope breaks down and the chromosomes lie free in the cytoplasm
32
Describe what happens during metaphase
In metaphase, the spindle has captured all the chromosomes and lined them up at the middle of the cell, ready to divide. All the chromosomes align at the equator of the cell.
33
Describe what happens during anaphase
Spindle fibres contract and the centromeres divide. Sister chromatids separate into 2 distinct chromosomes and are pulled to opposite poles of the cell. Spindle fibres break down
34
Describe what happens during telophase
Chromatids reach opposite poles on the spindle. They uncoil and become long and thin again. They're now called chromosomes again. A nuclear envelope forms around each group of chromosomes so there are now two nuclei. The cytoplasm finishes dividing and there are 2 daughter cells that are genetically identical.
35
What is cytokinesis?
Division of the cell cytoplasm
36
What is cancer?
A tumour that invades surrounding tissues
37
What is the process of cell fractionation?
1. Tissue cut up, placed in cold, isotonic buffer solution (stops enzyme activity, avoids osmosis and artefact development, maintains pH) 2. Cells and solution placed in homogeniser - resultant fluid is homogenate 3. Homogenate filtered to remove complete cells & debris 4. Filtered homogenate placed in ultracentrifuge which separates fragments
38
What is the purpose of cell fractionation?
The process where cells are broken up and the different organelles they contain are separated out.
39
What is homogenisation?
Breaking up cells by putting them into an ice cold isotonic buffer solution.
40
Why are cells put into an isotonic ice cold buffer solution during homogenisation?
The cells are put in a buffer solution to control the pH and the solution is ice cold to stop enzyme activity. The solution is isotonic to stop osmosis so the cell doesn't become turgid or flaccid.
41
In what order are the organelles releases during centrifugation
nucleus/chloroplast/mitochondria/lysosome/ribosome
42
What is centrifugation?
Centrifugation works by spinning the sample to separate out components of the cell according to size
43
What happens during ultracentrifugation?
The liquid (homogenate) is poured into a tube. The tube is put into a centrifuge and is spun at a low speed. The heaviest organelles go to the bottom of the tube by the centrifuge. They form a pellet. The rest of the organelles stay suspended in the fluid above the sediment, this is called the supernatant. The supernatant is drained off and poured into another tube and spun again at a higher speed.
44
Advantages of optical microscopes
Cheap and can use live specimens
45
How to prepare a slide (4)
1. Pipette a drop of water onto slide 2. Use tweezers to place a thin section of specimen on top of droplet. 3. Add a drop of stain 4. Add a cover slip at an angle -remove bubbles
46
How to calibrate eyepiece graticule
1 - Use a stage micrometer, special slide with etched scale - line up scales on graticule and stage micrometer. 2 - You can then calculate the length of divisions on eyepiece graticule. e.g. x40 gives 25um per graticule unit e.g. x400 gives 25/10um per graticule unit
47
Function of flagellum
Tail like structure which rotates to move the cell
48
3 details about viruses
Non living/Acellular Consist of Nucleic Acid Enclosed in a protective protein coat (capsid)
49
What is the mitotic index?
The proportion of cells in a tissue sample that are undergoing mitosis
50
How do you calculate mitotic index
Number of cells in mitosis/total number of cells
51
2 effects of carcinogen on health
Cause DNA in a cell to mutate - might make cell go through mitosis in uncontrolled way Uncontrolled cells (cancer) can grow into tumours - disrupt other cells, organs or systems
52
Benign tumour
Do not spread, but damage tissue as tumour grows
53
Malignant tumour
Spread through body by metastatis via bloodstream
54
2 Types of carcinogens
1 - Chemical: Tobacco, tar, asbestos and lead 2 - Ionising Radiation: X ray, UV, gamma, nuclear (A,Beta)
55
What is a mutation?
Rare random change in the DNA sequence - change in amino acid sequence - change in protein - change in phenotype
56
3 biological causes of cancer
Viral (Hep B and C - liver cancer) HPV - cenical cancer Genetic causes
57
Treatments of cancer
G1 - Chemotherapy targets the synthesis of enzymes required for cell growth and DNA replication. Without the right enzymes cells cannot enter S phase and so kills itself by aptosis - death of cells

BIOLOGY A LEVEL (7 decks)

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