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1
Q

structure and functions of microtubules

A

structure:
hollow tubes made out of tubulin proteins
(9+2 formation in cilia and flagella)

function:
forms spindle fibres to pull apart sister chromatids in anaphase
forms track for motor proteins to transport vesicles
forms cilia (to waft mucus)
forms flagella (for sperm/bacteria movement)

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2
Q

all membrane bound organelles

A

nucleus
mitochondria
RER and SER
golgi apparatus and vesicles
lysosomes and peroxisomes
vacuoles
chloroplast

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3
Q

non membrane bound organelles

A

ribosomes
centrioles
cytoskeleton
nucleolus

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4
Q

what is the structure of a prokaryote
(from out to in)

A
  • flagella (made of microtubules) for movement
  • pili (hair-like structures) attaches prokaryotes together
  • slime capsule protects immune system
  • peptidoglycan cell wall to shape cell
  • plasma membrane controls what enters and exits cell
  • cytoplasm (gel like substance) site of metabolic reactions
  • circular DNA (free floating) controls cell activity
  • plasmid DNA can give antibiotic resistance that can be shared between bacteria
  • 70s ribosomes site of protein synthesis
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5
Q

transverse
vs
longitudonal

A

transverse = horizontal across structure
longitudonal = vertical along structure

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6
Q

osmosis

A

net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane

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7
Q

Water potential (Ψ)

A

how concentrated a solution is
(pure water has the highest water potential of 0)
(adding solute to a solution makes it more -)

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8
Q

hypotonic solution meaning

A

the solution has a higher water potential (more pure) than the cell

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9
Q

plant vs animal cell in a hypotonic solution

A

water moves in to cell (down Ψ gradient)
plant becomes turgid (as cell wall strong)
animal cell bursts (lysis)

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10
Q

hypertonic solution

A

solution has a lower water potential than the cell

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11
Q

plant vs animal cell in a hypertonic (low water potential solution)

A

water moves out of cell into the solution

plants becomes plasmolysed#
animal cell shrinks

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12
Q

endosymbiotic theory

A

mitochondria and chloroplast where once prokaryotes that got engulfed by eukaryotes

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13
Q

what evidence backs the endosymbiotic theory

A

mito and chloro has:
- double membrane
- has its own circular DNA
- has 70s ribosomes
- they replicate independently

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14
Q

active transport

A

movement of molecules or ions against a concentration gradient using ATP and carrier proteins

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15
Q

prokaryotes vs eukaryotes

A

-prokaryote has no nucleus
-prokaryotes lack membrane bound organelles (mitochondria)
- prokaryotes have 70s ribosomes
- eukaryotes have 70s ribosomes
- prokaryotes reproduce via binary fission
- eukaryotes reproduce by meiosis

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16
Q

DNA vs RNA

A
  • DNA is double stranded
  • RNA is single stranded
  • DNA has deoxyribose (lack an O)
  • RNA has ribose
  • DNA has thymine base
  • RNA has uracil base
  • DNA store genetic info
  • RNA transfers genetic info
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17
Q

mitosis vs meiosis

A
  • mitosis is for growth and repair of tissues
  • meiosis is for formation of gametes
  • mitosis has one division
  • meiosis has two division
  • mitosis produces 2 diploid cells
  • meiosis produces 4 haploid cells
  • mitosis forms identical cells
  • meiosis forms non-identical cells
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18
Q

meiosis 1 and 2 steps

A

meioisis 1:
prophase 1: chromosomes condense and become visible, homologous chromosomes pair up, crossing over happens
metaphase 1: pairs line up at center
anaphase 1: spindle fibres pull homologous pairs apart to poles, sister chromatids remain together
telophase 1: cell membrane reforms splitting cell into two haploid cells
meiosis 2:
prophase 2: chromosomes condense and visible
metaphase 2: chromosomes align at the center
anaphase 2: sister chromatids separated by spindle fibres
telophase 2: cell membrane reforms splitting cells

final product= four non-identical haploid gametes

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19
Q

nucleotides structure

A
  • phosphate group (circle)
  • pentose sugar
  • nitrogenous base (rectangle)
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20
Q

phosphorylated nucleotides

A

nucleotide that contains more than one phosphate group (e.g ADP and ATP)

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21
Q

drawing improvements

A
  • use sharp pencil
  • use clean single lines (no overlapping)
  • no colouring or shading anything
  • use horizontal lines for labels (no arrows)
  • state magnifications
  • add a title
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22
Q

transcription 6 marker

A

in nucleus
DNA gyrase unwind double helix
DNA polymerase unzips H bonds between complimentary nitrogenous bases
exposing template strand
polymerase moves along template strand
using complimentary base pairing to form a complimentary mRNA strand
RNA nucleotides form phosphodiester bonds
mRNA exits nucleus via nuclear pores

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23
Q

translation 6 marker

A

occurs at ribosomes (RER) and cytoplasm
mRNA strand binds to ribosomes
mRNA sequence read in codons
tRNA carrying specific amino acids binds to mRNA anticodon (complimentary to codon)
ribosomes catalyses peptide bonds forming between adjacent amino acids
the makes a polypeptide chain
this carries on till the stop codon reached, so polypeptide is released

24
Q

what happens after translation

A
  • RER folds proteins into secondary/tertiary structures
  • protein is packaged into transport vesicle and transported to golgi apparatus via motor proteins and cytoskeleton
  • proteins modified at golgi apparatus
    (adds carbohydrate to form glycoprotein)
  • protein packaged into secretory vesicle
  • moves out of cell via motor proteins along cytoskeleton
  • vesicle fuses w plasma membrane to secrete protein by exocytosis
25
how does genetics code for anything
three bases form a codon which codes for a specific amino acid there are 64 possible codons but only 20 amino acids so the code is - degenerate (more than one codon can code for the same amino acid) - universal (the same codon codes for the same proteins in most organisms) - non overlapping (bases r read in sets of three only)
26
why do cells need to be stained before viewing
increases contrast between different organelles/cells in a specimen so components are more visible and easily distinguished
27
resolution
the ability for a microscope to distinguish between structures very close together
28
sucrose overview
disaccharide: alpha glucose + fructose joined by 1,2 alpha glycosidic linkage soluble for transport in phloem non-reducing sugar so chemically stable energy rich (good for plant resp)
29
what reaction breaks down molecules
hydrolysis adding water to separate molecules
30
cellulose overview
polysaccharide: beta glucose joined by 1,4 beta glycosidic linkage every other b glucose is flipped 180 to allow strong H bonding with other chains straight and unbranched chain forms micro and macrofibrils and plant cell walls high tensile strength (resists turgor pressure) fully permeable (allows solutes in) insoluble (structural support)
31
amlyopectin overview
polysaccharide: alpha glucose 1,4 and 1,6 alpha glycosidic linkage (straight chain has 1,4 and branched chain had 1,6) branched (can be hydrolysed for energy quickly) insoluble (doesn't affect cell water potential) component of starch (energy store in plants for winter)
32
amylase enzyme overview
enzyme that breaks down starch into maltose has Cl- cofactor to activate enzyme
33
glycogen overview
polysaccharide: alpha glucose 1,4 and 1,6 alpha glycosidic linkage (1,4 in chains and 1,6 in branches) highly branches (hydrolysed quickly for energy release) energy store in humans insulin protein forms glycogen glucagon protein breaks down glycogen into glucose
34
what elements are found in what biomolecules
carbohydrates: C, H, O proteins: C, H, O, N, S lipids: C, H, O nucleic acid: C, H, O, N, P
35
iodine test for starch
use mortar and pestle to smush sample and mix with distilled water place sample on spotting tile add iodine solution (I- in KI) to sample + test: brown to blue/black
36
benedicts test for reducing sugars
crush and dissolve sample in water add to test tube with equal amounts benedicts reagent heat test tube at 80*C in water bath for 3 mins + test: blue to brick red
37
benedicts test for non reducing sugars
first test for reducing (benedicts + water bath) when test comes back negative (blue) get a new test tube add 10cm3 of HCL (hydrolyses non-reducing sugars into monosaccharides) and heat at 40C neutralise sample by adding 10cm3 NaOH retest using benedicts reagent in 80*C water bath for 5min + test: blue to brick red
38
biurets test for proteins
crush and dissolve sample in distilled h20 add 5 drops of NaOH to sample in test tube to make solution alkali add biurets reagent (CuSO4) and mix + test: blue to lilac
39
ethanol emulsion test for lipids
crush sample and dissolve in distilled water add ethanol to sample to dissolve lipids add distilled water + test: clear/colourless to cloudy (milky-white) emulsion
40
how is energy stored in plants vs animals
plants: starch (amylose and amylopectin) humans: glycogen
41
what makes glycogen (polysaccharide of alpha glucose) a good store of energy
insoluble so no effect on a cells water potential metabolically inactive compact so can store lots of energy is small space highly branched to be hydrolysed for a glucose when needed
42
maltose
a glucose + a glucose 1-4 glycodisic linkage (reducing sugar)
43
lactose
B glucose + galactose B 1-4 glycosidic linkage (reducing sugar)
44
sucrose
a glucose + fructose a 1-2 glycosidic linkage (non reducing)
45
lipids overview
macromolecules contain C, H, O insoluble in water but soluble in ethanol - triglycerides - phospholipids - cholesterol form by condensation reactions between glycerol and fatty acids forms ester bonds (esterification reaction)
46
phospholipids overview
1 glycerol, 2 fatty acids, 1 phosphate ester bond between glycerol and fatty acids phosphodiester bond between phosphate and glycerol hydrophillic head (outward facing) hydrophobic tails (inwards facing) forms a selectively permeable membrane bilayer
47
triglycerides overview
one glycerol, three fatty acids joined by ester bonds energy store (Has a higher energy store per gram as a lipid compared to carbs) insoluble so has no effect on cell water potential acts as thermal insulator and protection barrier as triglycerides stored in adipose tissue under skin protects and surrounds organs
48
cholesterol overview
lipid steroid (similar to hormones) made of 4 hydrocarbon rings regulated membrane fluidity (binds to phospholipid tail, increasing packing of membrane, reducing fluidity) makes steroid hormones (oestrogen and testosterone) makes vit-D for healthy bones makes bile salts to digest fats in small intestines
49
general protein (amino acid) structures
Central carbon R to the bottom H at the top NH3 at the left COOH at the right H ! NH3 - C - COOH ! R
50
proteins overview
formed by amino acids held together by peptide bonds 4 structures of a protein (pri, sec, tert, quat) their R group determines it function and shape
51
globular proteins
-round/compact -water soluble E.G; insulin, haemoglobin, amylase
52
fibrous proteins
-long and rope like -insoluble -strong -flexible (good for structural support) E.G; collagen, keratin, elastin
53
conjugated proteins
has a prosthetic group and a globular protein held together by ionic bonds (e.g: heamoglobin has 4 Fe2+ (haem) groups in its structure)
54
protein structures order w given bonds
primary- sequence of amino acids in a protein chain (has peptide bonds) secondary- folding of protein chain into beta pleated sheet or alpha helix (has H bonds between NH and OH) tertiary- 3d folding of one protein chain quaternary- many polypeptide chains arranged to make functional protein (H, ionic, disulfide)
55
percentage change equation
Percent Change= (New Value−Old Value)/old value x100 ​
56

biology A-LEVEL (24 decks)

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