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cell structure and division Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

function of cell surface membrane

A

partially permeable;
physical barrier;
recognition;
transport

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2
Q

structure of cell surface membrane

A

found on the surface of animal cells, inside the cell wall of plant cells; made mostly of phospholipids and proteins

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3
Q

function of nucleus

A

stores genetic info for protein (polypeptide) production; controls cells’ activities by controlling the transcription of DNA (makes instructions to make proteins); pores allow substances to move between the nucleus and the cytoplasm; nucleolus makes ribosomes and pRNA; where DNA replication occurs

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4
Q

structure of nucleus

A

large organelle surrounded by a double membrane nuclear envelope, which contains many pores;
nucleus contains chromosomes (made from protein-bound linear DNA); and a nucleolus

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5
Q

structure+function of nuclear envelope

A

double-membrane surrounding the nucleus, which controls exit and entry of materials

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6
Q

function of mitochondria

A

site of aerobic respiration; where ATP is produced; releases energy

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7
Q

structure of mitochondria

A

oval-shaped with a double membrane, inner membrane is folded to form cristae;
inside the cristae is the matrix which contains the enzymes involved in respiration

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8
Q

structure+function of cristae

A

folds in the inner membrane of the mitochondria; they are the site of oxidative phosphorylation

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9
Q

function of golgi apparatus

A

processes and packages new lipids and proteins; makes lysosomes

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10
Q

structure of golgi apparatus

A

fluid-filled, membrane-bound flattened sacs; vesicles are found at the edges

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11
Q

4 functions of golgi apparatus

A
  1. produces secretory enzymes and carbohydrates
  2. stores and modifies proteins & triglycerides
  3. forms vesicles for transporting proteins and triglycerides
  4. forms lysosomes
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12
Q

function of vesicles

A

stores lipids and proteins made by the golgi apparatus and transports them out of the cell via the cell-surface membrane

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13
Q

structure of vesicles

A

small fluid-filled sac in the cytoplasm, surrounded by a membrane; produced by the golgi apparatus

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14
Q

function of ribosomes

A

site of protein synthesis

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15
Q

structure of ribosomes

A

small organelle, floats freely in the cytoplasm, or is attached to the rough endoplasmic reticulum; made of proteins and RNA; not surrounded by a membrane

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16
Q

function of rough endoplasmic reticulum

A

folds and processes proteins+glycoproteins that have been made at the ribosomes

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17
Q

structure of rough endoplasmic reticulum

A

system of membranes enclosing a fluid-filled space; covered in ribosomes

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18
Q

how does the structure of the rough endoplasmic reticulum help enable synthesis of proteins?

A

the rough endoplasmic reticulum has ribosomes and a large surface area

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19
Q

function of smooth endoplasmic reticulum

A

synthesises and processes lipids;

site of synthesis , storage and transportation of lipids and carbohydrates.

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20
Q

structure of smooth endoplasmic reticulum

A

system of membranes enclosing a fluid-filled space; no ribosomes

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21
Q

function of lysosomes (animal only)

A

contains digestive/hydrolytic enzymes (lysozymes) surrounded by membrane;
used to digest invading cells or break down worn components of the cell

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22
Q

structure of lysosomes (animal only)

A

round membrane-bound organelle; type of golgi vesicle

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23
Q

function of chloroplasts (plant only)

A

site of photosynthesis;
some in grana others in stroma

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24
Q

structure of chloroplasts (plant only)

A

small, flattened structure found in plant and algal cells;
surrounded by a double membrane;
has thylakoid membranes which are stacked up to form grana and stroma

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25
Q

what are grana?

A

stacks of thylakoids found in the chloroplast.

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26
Q

what are thylakoids?

A

flattened sacs in the chloroplast, containing chlorophyll;
site of the light-dependent reaction for photosynthesis

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27
Q

what is the stroma?

A

the matrix of the chloroplast in a plant cell;
site of the light-independent reaction for photosynthesis

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28
Q

function of cell wall (plants and prokaryotic cells)

A

provides rigidity or integrity to the cell and stops the cell from bursting by exerting inward pressure to prevent osmosis;
this enables turgidity which makes parts of the plant semi-rigid

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29
Q

structure of cell wall (plants and prokaryotic cells)

A

rigid structure that surrounds cells in plants, algae and fungi;
made of cellulose in plants and algae, made of chitin in fungi, made of murein in prokaryotic cells

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30
Q

function of vacuole (plants only)

A

helps maintain pressure in the plant, keeps it turgid;
stops plant wilting;
stores sugars and amino acids which can act as a temporary food storage;
in petal cells, it can store pigments to attract pollinating insects.

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31
Q

structure of vacuole (plants only)

A

membrane-bound organelle found in cytoplasm;
contains cell sap (weak solution of sugar and salts);
surrounding (single) membrane is called the tonoplast

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32
Q

function of plasmids (prokaryotic cells)

A

contains genes for antibiotic resistance;
acts as a vector;
can be passed between prokaryotic cells via pilli (short hairs)

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33
Q

structure of plasmids (prokaryotic cells)

A

small loop of DNA; amounts vary in each cell

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34
Q

function of circular DNA (prokaryotic cells)

A

controls cell’s activities (transcription of proteins)

35
Q

structure of circular DNA (prokaryotic cells)

A

one long, coiled up strand that floats free in the cytoplasm; not attached to histones

36
Q

function of flagellum (prokaryotic cells)

A

rotates to make cell move (not present in all prokaryotic cells)

37
Q

structure of flagellum (prokaryotic cells)

A

hair-like structure; made of flagellin

38
Q

function of capsule (prokaryotic cells)

A

protects bacteria from attack by immune system

39
Q

structure of capsule (prokaryotic cells)

A

made of secreted slime

40
Q

Describe viral replication [3 marks]

A

attachment proteins attach to receptors;
viral/nucleic acid enters cell and replicates in the cell;
cell produces viral protein;
virus assembled and released

41
Q

Describe binary fission [3 marks]

A

replication of circular DNA and plasmids;
cell enlarges and DNA moves to opposite poles;
division of cytoplasm;
2 daughter cells produced

42
Q

how to calculate magnification

A

I=AM

43
Q

optical microscopes

A

uses light to look at cells and larger organelles;
stained to provide contrast;
prep is simple and quick;
natural colour of living tissues can be observed;
only magnifies up to x1500;
resolution is restricted to 0.2(micrometers) so cannot view smaller organelles due to longer wavelengths of light

44
Q

2 types of electron microscopes

A

scanning (SEM)
transmission (TEM)

45
Q

electron microscopes

A

much higher resolution than optical microscopes (up to 0.0002 micrometers) due to the electrons having a much shorter wavelength;
magnifies x1500000;
use magnets (affected by magnetic field);
preparation is longer and more complex;
prep may distort specimen;
images are black + white;
cannot view living cells

46
Q

scanning microscopes

A

beam of e- reflected off the surface (3d image);
whole cells, tissues and organisms can be viewed;
lower resolution than TEM

47
Q

transmission microscopes

A

beam of electrons pass through specimen (focused by electromagnets);
specimen needs to be heavily stained (with heavy metals);
requires thinly sliced specimen;
viewed in a vacuum;
higher resolution than SEM

48
Q

cell fractionation (describe)

A
  1. homogenisation–>grinding up the cells in a blender
    CONDITIONS:
    >ice cold
    >isotonic (solution has same water potential as cells)
    >have a buffer added
  2. filtration (through a gauze)
  3. ultracentrifugation–>separate organelles by mass-density
    >filtered solution centrifuged at low speed
    >respin supernatant at higher speed
    > process repeated at higher speeds
49
Q

cell fractionation (explain)

A
  1. homogenisation–> break opens the cells, breaking up the plasma membrane to release the organelles
    > ice cold: reduces enzyme activity, preventing organelles from being broken down
    > isotonic solution: prevents damage to organelles by osmosis (prevents organelle lysis)
    >have a buffer added: maintain pH of a solution to prevent proteins denaturing
  2. filtration–>take out debris e.g. connective tissue and whole cells
  3. ultracentrifugation
    >centrifuge at low speed–separate out heaviest organelles e.g. nuclei
    >respin at higher speed– remove heaviest organelles from supernatant e.g. chloroplast into the pellet
    >process repeated at higher speeds–to remove the heaviest organelles in pellets each time
50
Q

cell cycle

A

G1, synthesis, growth 2 [interphase] and mitosis

51
Q

G1>growth 1

A

cell gets bigger;
volume and mass increases (more organelles);
mitochondria (needed to produce ATP and release energy to allow the spindle fibres to pull the chromosomes to opposite sides of the cell

52
Q

synthesis

A

DNA replicates

53
Q

G2>growth 2

A

cell keeps growing and protein synthesis increases to make spindle fibres for mitosis

54
Q

mitosis

A

cell division;
for growth and repair;
4 stages (PMAT) and cytokinesis

55
Q

prophase

A

chromosomes condense and become shorter and more visible;
chromosomes appear as two sister chromatids and are joined at the centromere;
centrioles move to the poles, begin to produce spindle fibres;
nuclear envelope breaks down

56
Q

metaphase

A

chromosomes become attached to the spindle fibres at the centromere;
chromosomes line up along the equator

57
Q

anaphase

A

the centromere splits;
sister CHROMATIDS are pulled to opposite poles of the spindle;
CHROMATIDS appear appear ‘v’ shaped

58
Q

telophase (and cytokinesis)

A

chromatids are chromosomes again;
become long and thin;
nuclear envelope reforms;
division of cytoplasm (cytokinesis)

59
Q

mitotic index

A

proportion of cells undergoing mitosis
mitotic index=number of cells in mitosis/total no. of cells observed x100

60
Q

Describe the appearance and behaviour of chromosomes during mitosis [5 marks]

A

prophase: chromosomes are visible and condensed
metaphase: chromosomes line up across the equator
anaphase: centrioles break up centromere; sister CHROMATIDS are pulled to opposite poles by spindle fibres
telophase: chromatids uncoil themselves as they are surrounded by the nuclear envelope

61
Q

cancer

A
62
Q

role of cell membrane

A

acts as a barrier between the cell and its environment;
controls what substances enter and exit the cell;
partially permeable membrane-> allow some substances through but not others;
respond to environment-> cell surface receptors;
membranes around organelles divide the cell into compartments to stop the enzymes from leaving into the cytoplasm

63
Q

membrane structure

A

phospholipid bilayer; hydrophilic PL head, hydrophobic fatty acid tail;
centre is hydrophobic so water-soluble substances cannot pass through

64
Q

cholesterol in a cell membrane

A

provides stability and strength;
binds to the tails of phospholipids causing them to pack together

65
Q

channel proteins in a cell membrane

A

form pores in the membrane;
different channel proteins facilitate different charged particles;
transport ions and polar molecules
(water-soluble; cannot diffuse through membrane because centre of bilayer is hydrophobic)

66
Q

function of carrier proteins in a cell membrane

A

transports large molecules
1. large molecule attaches to a carrier protein
2. protein changes shape
3. releases the molecule on the opposite side

67
Q

receptor proteins in the cell membrane

A

allow the cell to detect chemicals released by other cells (e.g. toxins)

68
Q

ATP synthase

A

protein enzyme that catalyses ATP production

69
Q

membrane folding (adaption of membrane)

A

increases surface area;
increase the number of carrier/channel proteins;
increases rate of diffusion

70
Q

‘fluid-mosaic’ structure

A

phospholipid molecules form continuous, double layer;
‘fluid’ because the phospholipids are always moving;
proteins and cholesterol are scattered through the bilayer like tiles in a mosaic

71
Q

diffusion

A

net movement of particles from an area of higher concentration to an area of lower concentration
OR
net movement of particles down its concentration gradient
*passive process

72
Q

simple diffusion

A

diffusion that does not require the assistance of membrane proteins

73
Q

facilitated diffusion

A

requires the assistance of membrane proteins to speed up rate of diffusion

74
Q

factors that affect rate of simple diffusion

A

concentration gradient: the higher it is, the higher the rate of diffusion;
the thickness of exchange surface: shorter/longer diffusion pathway;
surface area; the larger the surface area, the faster the rate of diffusion

75
Q

factors that affect rate of facilitated diffusion

A

concentration gradient: the higher the concentration gradient, the faster the rate of facilitated diffusion
number of channel or carrier proteins: when all proteins are in use, facilitated diffusion can’t happen faster

76
Q

osmosis

A

net movement of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential

77
Q

water potential

A

the likelihood of water particles to diffuse in or out of a solution
(pure water has highest water potential)

78
Q

factors that affect the rate of osmosis

A

water potential gradient: the higher the water potential gradient, the faster the rate of osmosis;
thickness of the exchange surface: osmosis pathway;
surface area: the larger the surface area, the fast the rate of osmosis

79
Q

active transport

A

the movement of substances across a cell membrane against their concentration gradient which requires energy

80
Q

process of active transport

A

molecule attaches to carrier protein, the protein changes shape and the molecule is released on the opposite side of the membrane

81
Q

what energy does active transport need?

A

ATP; produced by respiration
ATP goes under a hydrolysis reaction, splitting into ADP and inorganic phosphate which releases energy so solutes can be transported

82
Q

co-transporters

A

a type of carrier protein that binds two molecules at once;
the concentration gradient of one of the molecules is used to move the other molecule against its own concentration gradient

83
Q

factors affecting the rate of active transport

A

speed of individual carrier proteins;
number of carrier proteins;
rate of respiration and availability of ATP

biology (4 decks)

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