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biology > cell structure > Flashcards

cell structure Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define Magnification

A

How many times bigger the image is than the specimen (object)

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2
Q

Define Resolution

A

Minimum distance apart that two objects can be in order for them to appear as separate items

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3
Q

what is the equation for magnification?

A

m = I/A

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4
Q

what is cell fractionation?

A

the process where cells are broken up and the different organelles they contain are separated out

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5
Q

why is the tissue placed in a cold, buffered, isotonic solution?

A

cold- reduce enzyme action that might break down organelles

buffered- so that pH does not denature proteins

isotonic-to prevent bursting or shrinking via osmosis

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6
Q

what is homogenation?

A

cells are broken up by homogeniser which releases organelles from the cell. The homogenate is then filtered to remove large debris

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7
Q

what is ultracentrifugation?

A
  1. where organelles are separated by a centrifuge.
  2. Filtrate is spun at low speed at first to allow heaviest organelles to form sediment.
  3. liquid at top is removed to leave just sediment.
  4. liquid is spun at higher speed and process is repeated so that each time, the next heaviest organelle is separated out
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8
Q

State the maximum magnification for an optical microscope

A

x 1500

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9
Q

State the maximum resolution for an optical microscope

A

0.2 µm

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10
Q

Name 3 pros of optical microscopes

A

Easy and cheap to operate
Can have living specimens
can see in colour

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11
Q

Name 2 cons of optical microscopes

A

Low resolution & magnification so can’t see organelles smaller than 0.2 µm (e.g. ribosomes, endoplasmic reticulum and lysosomes)

Specimens often need staining to show specific organelles

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12
Q

Why does optical microscopes have a maximum resolution of 0.2 µm?

A

because of the long wavelength of light rays

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13
Q

what is a TEM?

A

Transmission electron microscope
consists of an electron beam focused on to specimen. Some parts absorb so appear darker. This creates a 2d image

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14
Q

State the maximum resolution for a transmission electron microscope

A

0.1 nm

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15
Q

State the maximum magnification for a transmission electron microscope

A

x 10 000 000

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16
Q

Name a pro of transmission electron microscopes

A

Has highest resolutions & magnification
so can see internal structure of organelles e.g. chloroplasts

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17
Q

Name 4 cons of transmission electron microscopes

A

can not observe living organisms as system must be in a vacuum

complex staining process

not in colour

may contain artefacts which are things that appear in the image as a result of the preparation process.

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18
Q

what is a SEM?

A

Scanning electron microscope that directs a beam of electrons on to surface of specimen, forming a 3D image.

19
Q

what 2 instruments are used to measure the size of objects?

A

eyepiece graticule and stage micrometer

20
Q

what is the structure and function of the nucleus?(5)

A

nucleus contains cell’s hereditary material in the chromosomes

nuclear envelope is a double membrane that surrounds nucleus controlling entry and exit of materials

nuclear pores allow passage of large molecules e.g. mRNA out of the nucleus

nucleoplasm is jelly like substance that makes up bulk of nucleus

nucleolus manufactures ribosomal RNA and ribosomes.

21
Q

What are chromosomes made of?

A

DNA bound to histone proteins

22
Q

what is the structure and function of the mitochondria?(4)

A

Have double membrane, the inner membrane is highly folded & called cristae

cristae provide large surface area for attachment of enzymes involved in respiration

Inner section is called matrix containing protein lipids ribosomes and DNA that allow for production of proteins

mitochondria are the site of aerobic respiration so are plentiful in cells that need ATP

23
Q

what is the structure and function of chloroplasts?(4)

A

contain double membrane that is highly selective

grana are stacks of thylakoids that contain chlorophyll for LDR of photosynthesis. membrane provides large surface area for attachment.

stroma is fluid filled matrix where LIR of photosynthesis occurs

contains DNA and ribosomes so can easily produce proteins.

24
Q

what is the structure and function of the rough endoplasmic reticulum?(3)

A

network of flattened membrane bound sacs called cisternae

covered in ribosomes

provides large surface area for synthesis of proteins and glycoproteins and transports these.

25
Q

what is the structure and function of the smooth endoplasmic reticulum?(2)

A

no ribosomes, continuous with RER

synthesises, stores and transports lipids and carbohydrates

26
Q

what is the structure and function of the Golgi apparatus?(3)

A

Stacks of membrane-bound flattened sacs called cisternae

transports, modifies and stores lipids and proteins

form lysosomes by pinching off cisternae

27
Q

What is a lysosome and what is its function?(4)

A

vesicles containing enzymes e.g. lysozymes

hydrolyse material ingested by phagocytic cells

release enzymes outside cell so material outside cell can be destroyed

digest worn out organelles so that useful chemicals can be reused

28
Q

what is the structure and function of ribosomes?(2)

A

two subunits each containing ribosomal RNA and protein.

sight of protein synthesis

29
Q

what are the 2 types of ribosomes and where are they found?

A

80S- in eukaryotic
70S- in prokaryotic

30
Q

what is the function of a cell wall?

A

provide mechanical strength to prevent cell bursting under osmotic pressure

31
Q

what is the difference between plant and fungal cell walls?

A

plant- made of cellulose
fungi- made of chitin

32
Q

what is the structure and function of the vacuole?(3)

A

fluid filled sac bound by membrane called tonoplast

support herbaceous plants by making cells turgid

contains sugars, amino acids that may be used as temporary food store

33
Q

name and explain 5 structures of prokaryotic cells

A

cell wall-protects against mechanical damage

capsule-protects and helps groups of bacteria stick together

cell-surface membrane-controls entry and exit

circular DNA-holds genetic information

plasmid-contains survival genes

34
Q

Name 4 structural differences between eukaryotes and prokaryotes

A

prokaryotes:
Smaller ribosomes (70s type)

No true nucleus (free, floating circular DNA)

DNA not associated with proteins

No membrane-bound organelles

Cell wall made from the glycoprotein murein

35
Q

what are viruses?

A

acellular (no organelles)
non living particles(They cannot reproduce independently)

36
Q

Name 5 features of viruses

A

Contain core of genetic material - either DNA or RNA

Have protein coat around core called capsid

Have attachment proteins which stick out from edge of the caspid

lipid envelope

may have flagella

37
Q

What happens in interphase?

A

G1- growth of cell
S1-synthesis of organelles
G2-further growth

the two copies of DNA are joined by a centromere

38
Q

What happens in prophase?

A

chromosomes condense and become visible

nucleolus disappears and nuclear envelope breaks down

39
Q

What happens in metaphase?

A

chromatids joined by a centromere line up along the equator of the cell

40
Q

What happens in anaphase?

A

spindle fibres from centrioles attach to centromeres

centromeres divide and each chromatid is pulled to opposite poles of the cell

41
Q

What happens in telophase?

A

chromosomes elongate and become thinner, leaving chromatin

nucleolus and nuclear envelope reform

42
Q

what is cytokinesis?

A

when the cytoplasm and membrane divide

43
Q

what is cancer?

A

abnormal and uncontrolled cell division

biology (7 decks)

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