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A level > OCR A BIOLOGY MODULE 2 > Flashcards

OCR A BIOLOGY MODULE 2 Flashcards

1
Q

Eukaryotic & Prokaryotic Cells

A

Similarities: Both contain ORGANELLES

  • cell membrane CONTAIN PHOSPHOLIPID BILAYERS
  • BILAYER controls PASSAGE of SUBSTANCES , across EXCHANGE SURFACES

Differences: Prokaryotic made of SINGLE celled ORGANISM e.g BACTERIA

  • Eukaryotic made of COMPLEX organisms e.g animals , plants , fungi , cells reproduce via MITOSIS/MEIOSIS
  • Prokaryotic are NON MEMBRANE bound organelles , cells reproduce via BINARY FISSION
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2
Q

Nucleus & Nucleolus

A

Nuclear envelope = DOUBLE MEMBRANE structure , MANY PORES
- BOTH INNER & OUTER membranes are ‘ PHOSPHOLIPID BILAYERS’
-PORES in nuclear envelope CONTROL PASSAGE OF IONS , MOLECULES & RNA between NUCLEOPLASM & CYTOPLASM
Structure of Nucleus:
- Nucleoplasm SEMI SOLID fluid inside nucleus containing CHROMATID & NUCLEOLUS
- in EUKARYOTES , nucleus has LINEAR CHROMOSOMES , made of DNA
area WITHIN nucleus is called “ NUCLEOLUS”

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3
Q

function of nucleus

A
  • controls activities of cell
  • DNA contains instructions for synthesis of proteins
  • RNA joined together with associated proteins in nucleus = ribosomal sub unit
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4
Q

function of nucleolus

A
  • site where RIBOSOMES are made
  • immobilising Proteins
  • forming SIGNAL RECOGNITION
  • LARGEST SUB SHELL IN NUCLEUS
  • MADE OF PROTEINS, RNA & DNA
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5
Q

Functions of Ribosomes

A
  • FREE FLOATING CYTOPLASM attached to side of endoplasmic reticulum
  • very SMALL organelles made of PROTEIN SUB UNITS
  • NOT covered by MEMBRANE
  • responsible for PROTEIN SYNTHESIS
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6
Q

function of Endoplasmic reticulum and SER

A
  • series of INTERCONNECTED membranes SACS & TUBULES
  • Membrane of ‘ER’ is ‘PHOSPHOLIPID BILAYER EMBEDDED IN ‘proteins’
  • ‘SER’ HAS NO RIBOSOMES
  • ‘RER’ HAS MANY RIBOSOMES
  • ’ RER’ PROCESSES AND FOLDS PROTEINS
  • ‘SER’ PROCESSES AND MAKES LIPIDS
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7
Q

Importance of Cytoskeleton

A
  • cytoskeleton= network of protein FIBRES , performing DIFFERENT FUNCTIONs
  • functions:
  • maintaining shape of cell
  • securing some proteins in specific positions
  • allowing CYTOPLASM & VESICLES to move within cell
  • enabling cells with MULTI-CELLULAR organisms to MOVE
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8
Q

Protein Fibres of Cytoskeleton

A
  • MICROfilaments THICKEN CORTEX around INNER edge of cell
  • RESIST TENSION
  • intermediate filaments are THROUGHOUT cell = holding organelles in place
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9
Q

Microtubules

A
  • MAINTAIN SHAPE of cell

- RESIST COMPRESSIVE FORCE

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10
Q

Magnification

A
  • ENLARGING an object in appearance
    image size= how BIG object appears (mm)
    actual size= in micrometers (μm)
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11
Q

Calculating Magnification and Conversion Units

A 
magnification = image size / actual size 
1mm= 1000μm
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12
Q

Resolution

A
  • the ability to DISTINGUISH between 2 separate objects with CLARITY
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13
Q

Importance of Water

A
  • Reactant in cellular reactions e.g (Photosynthesis & Hydrolysis)
  • provides STRUCTURAL Support in cells
  • Keep organisms COOL
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14
Q

Properties of Water

A
  • Metabolic importance
  • high Specific Heat Capacity
  • high latent heat
  • cohesive
  • solvent uses
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15
Q

Chemical Elements in Biological Molecules

A

Carbohydrates: ‘ C ‘ , ‘ H2 ‘, ‘ O2 ‘
lipids: ‘ C ‘, ‘ H2 ‘, ‘O2’
Proteins: ‘ C ‘, ‘ H2 ‘, ‘ O2 ‘, ‘N’, ‘S’
Nucleic Acid: ‘ C ‘, ‘ H2 ‘, ‘ O2 ‘ , ‘ N ‘, ‘ P ‘

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16
Q

Monomers

A

SINGLE sub unit of life e.g. amino acid , nucleotide , monosaccharides

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17
Q

Polymers

A

formed from COMBINING MONOMERS via covalent bonding

- complex monomers e.g Proteins, DNA , Starch

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18
Q

Hexose vs Pentose Sugars

A
  • Pentose are Monosaccharides , 5 carbon atoms e.g RIBOSE

- Ribose , one of 3 main components of Nucleotides in ‘RNA’

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19
Q

Carbohydrates

A 
Monosaccharides are SIMPLE sugars 
e.g 
Glucose : Hexose sugar C6 H12 O6 , Energy released from respiration MAKES ATP
Galactose (Milk)
Fructose (fruit)
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20
Q

Alpha vs Beta Glucose

A
  • ISOMERS - have same MOLECULAR FORMULA , Varied atomic arrangement
  • Carbon atoms numbered from ‘1-6’
  • OH groups in different ORIENTATION (C1)
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21
Q

Examples of Carbohydrates

A

Starch: Polysaccharide formed via Condensation reaction of Alpha - Glucose molecules
Functions:
- Main energy storage in PLANTS (seeds)
- source of food for Human & Animals

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22
Q

Features of Starch

A
  • DO NOT change water potential on cell = INSOLUBLE in water

- Made of AMYLOPECTIN & AMYLASE

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23
Q

Amylopectin

A
  • Highly BRANCHED chain of Alpha- Glucose Monomers

- Branched Structure =Enzymes can access Glycosidic bonds & glucose quickly released

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24
Q

Amylose

A
  • LINEAR chain of Alpha-Glucose Mono,ers
  • Monomers are joined , glucose chains have HELICAL structure
  • Amylose strands CLOSE TOGETHER, good for STORAGE
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25
Q

Formation of Fatty Acids

A
  • TRIGLYCERIDES - type of Lipid used as ENERGY STORAGE MOLECULE
    Formation :
  • CONDENSATION of 1 molecule of GLYCEROL + 3 molecules of FATTY ACID
  • ESTER bonds form BETWEEN THEM
  • 1 water molecule RELEASED per Ester bond
  • 3 molecules of water released per TRIGLYCERIDE FORMED
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26
Q

Structure of Fatty acids

A
  • LONG ‘ Tails’ made from hydrocarbon chains 4-36 Carbon atoms
  • hydrocarbon ‘tail’ varies
  • glycerol binds to ‘central carbon atom; on FATTY ACID
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27
Q

Structure of Saturated fat

A
  • Carbon atoms not joined via double bond

- number of hydrogen atoms attached to carbon skeleton is MAXIMISED

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28
Q

function of saturated fat

A

-SOLID at room temp
- increases risk of Cardiovascular disease in humans
sources of saturated fat :
- cream , cheese , butter

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29
Q

structure of polypeptides (proteins)

A
  • made of amino acids
  • dipeptides formed via CONDENSATION of 2 amino acids
  • Polypeptides formed via CONDENSATION of Many amino acids
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30
Q

Structure of Amino Acids

A
  • each amino acid has - ‘central carbon atom’
  • groups bonded to ‘central carbon atom’:
  • NH2 (amino group)
  • COOH
  • H2
  • R ( side group)- varies with each amino acid
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31
Q

Amino acids

A

R groups- determine how ‘amino acids’ interacts & bonds with other amino acid in protein
essential amino acids: 20 types of amino acids in ALL organisms
- 9 essential in humans, via diet

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32
Q

amino acids

A 
Glycerin- example of amino acid , hydrogen atom in R group
no carbon atom in R group
Amino acid sequence:
-arranged in SPECIFIC sequence
- determined by gene encoding protein
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33
Q

Importance of Amino acid sequence

A
  • change in nucleotide sequence of gene coding = DIFFERENT amino acid added to GROWING protein chain
  • chain in amino acids on protein= change protein structure & function
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34
Q

Tertiary structure of Protein

A

R= side chain of amino acids
- interactions between groups create complex 3D protein
3D structure= coiled /folded
when protein loses 3D structure= No longer functional
weak & strong interactions determine shape

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35
Q

Ionic bonds

A

-charged amino acids have oppositely charged ions in side chain
forming strong ionic bonds with other charged amino acids
- RARE

36
Q

Disulfide bridges and hydrogen bonds

A
  • S-S covalent bond within protein containing CYS amino acid
  • Hydrogen bonds form between amino acids
    weak & strengthen when there are MANY
37
Q

Structure of Globular Proteins

A
  • spherical shape
  • tertiary structure = round structure
  • induced dipole - dipole forces & hydrogen bonds between DIFFERENT parts of Polypeptide chain help maintain Coiled shape
  • insoluble in water
38
Q

Functions of Globular proteins

A
  • messengers
  • enzymes
  • structural protein
    example: haemoglobin , insulin & DNA
39
Q

inorganic ions- Cations

A

ions in living organisms - obtained via nutrition
Cytoplasm& body fluids MAINTAIN optimum levels
- some ions have higher concentrations , lower concentration of toxic ions

40
Q

inorganic ion names

A
  • H+ = pH value= concentration of H+ ions
  • Na+ = transported across membrane of cells in intestine allows for co-transport of glucose & amino acids
  • Ca2+ - carries signals around organisms , maintain PD of cell membrane
  • K+ - found in tissues for propagation of action potentials in nervous tissue
  • NH4+ - metabolite amino acid , makes some nitrogen based compounds
  • excess NH4+ excreted as waste product UREA
41
Q

Test for Lipids & Protein

A

1) place sample in boiling tube with ETHANOL
2) shake well , leave upright for 2-3 mins
3)pour the solution into a boiling tube containing DISTILLED WATER
if Lipid is present - White/Milky layer forms

42
Q

Test for Sugars& Starch - Reducing sugars

A

1) Place 2ml of LIQUID substance in boiling tube
2) add 10 drops of Benedict ‘s solution
3) place in boiling water bath for 3 - 5 mins

43
Q

Test for Sugars & Starch - Non Reducing sugars

A

1) Boil in dilute HCl ( to hydrolyse sugar)
2) neutralise solution by adding sodium bicarbonate
3) repeat benedict’s test

Positive result for NON reducing sugar
Remain BLUE if NO SUGAR is present

44
Q

Colorimetry

A
  • allows for colour of substance to be QUANTIFIED

- shining light with a KNOWN WAVELENGTH range through a solution &recording what comes out the other side

45
Q

Biosensors

A
  • made of biological elements & a physiochemical detector
  • biological component is sensitive e.g. microorganisms , enzymes
  • biosensors produce electrical signals from BIOLOGICAL RESPONSES
46
Q

Chromotography

A
  • separates substances based on their INTERACTION to mobile & stationary phase
    mobile phase= solvent
    stationary phase= solid support
47
Q

chromotography

A
  • the more a substance is ATTRACTED to stationary phase , the LONGER it takes to reach the bottom of the column / LONGER to elute
  • separate substances leave column at DIFFERENT RATES
  • substances with LARGER RETENTION TIME interact STRONGLY with stationary phase
48
Q

DNA

A 
- DEOXYRIBONUCLEIC  ACID 
contains all genetic info
codes for proteins
in Eukaryotes= DNA is in nucleus/chloroplasts/mitochondria
Prokaryotes= DNA in form of plasmid
49
Q

RNA

A

synethises proteins

ribosomes formed from RNA & Proteins

50
Q

Role of mRNA

A

DNA uses messenger RNA for transfer of genetic info to cells

mRNA moves out of nucleus to ribosomes to make proteins

51
Q

DNA structure

A
  • made of 2 polynucleotide chains (double helix)
  • Sugar & Phosphate OUTSIDE helix
  • Nitrogen base INSIDE helix
  • Hydrogen bonds HOLD base pairs
52
Q

RNA Structure

A
  • SHORT polynucleotide chains ( 1 chain)

- made of RIBONUClEOTIDE linked by Phosphodiester bond

53
Q

Component of ATP

A
  • ADENINE - Nitrogenous bonds
  • RIBOSE- 5 carbohydrate- sugar
  • 3 PHOSPHATE groups
54
Q

Function of ATP

A
  • Small/ simple molecule

- ATP used to POWER ENERGY for cellular reactions

55
Q

DNA replication

A
  • DNA HELICASE binds to DNA , breaking hydrogen bonds between 2 strands
  • DNA helix UNWINDS , strands separate
  • free floating nucleotide form hydrogen bonds with complementary bases ( used as template)
  • DNA Polymerase forms ‘ PHOSPHODIESTER’ bonds between nucleotide
  • 2 new DNA strands SYTHESISED
56
Q

Transcription

A

1) Binding to RNA POLYMERASE
- enzyme allows transcription
- RNA polymerase BINDS to LOCUS of gene (target)
2) separation
- DNA helicase UNWINDS double strands , breaking hydrogen bonds
- DNA strands SEPARATE
- Bases of ‘target gene’ expose

57
Q

Transcription

A

3) Binding to Template Strands
- RNA Polymerase BINDS free floating RNA nucleotides to COMPLEMENTARY DNA STRAND
- RNA nucleotide form strand of mRNA(copy of gene)
4) Joining nucleotides
- Free floating nucleotides joined by RNA Polymerase
- Phosphodiester bond form between nucleotide forming strands of mRNA

58
Q

Transcription

A

5) STOP CODON
- RNA Polymerase reaches Triplet bond that signal STOP
- RNA STOPS separation of DNA & Producing mRNA
6) Removal of mRNA
- MRMA SEPARATED from template by RNA Polymerase
- Hydrogen bonds between strands of DNA REFORM

59
Q

Transcription

A

7) mRNA
- completed mRNA leaves nucleus to reach cytoplasm
- mRNA used in translation then SYTHESISED

60
Q

Enzyme Structure & Function

A
  • Enzymes catalyse reactions
61
Q

Factors affecting Enzyme action

A
  • pH- changing number of OH- & H+ surrounding enzyme changed TERTIARY STRUCTURE
  • Temp outside optimal range causes enzyme to denature ( Active site no longer fits in substrate so enzyme changes shape)
62
Q

Coenzyme

A
  • small molecules with increase activity of enzyme
  • bind to enzyme, causes conformational change
  • inorganic/organic molecules
  • e.g Vitamins
63
Q

Prosthetic groups

A
  • inorganic molecules
  • permanently bind to enzymes - forming part of structure
  • increasing rate of enzyme activity
64
Q

Structure of Phosphlipids

A
  • molecule with GLYCEROL , 2 FATTY ACIDS , PHOSPHATE LINKED HEAD GROUP
  • arranged in BILAYER 5-10 nm in thickness
  • Hydrophilic phospholipid head faced OUTWARDS
  • Hydrophobic fatty acids face INWARDS
65
Q

Function of Plasma membrane

A
  • defines border of cells

- partially permeable

66
Q

Structure of Cholesterol

A
  • Lipid sitting with Phospholipid in CORE of membrane
  • Not found in Bacterial cell membrane
  • rigid
  • Maintains shape of cell
67
Q

Fluid Mosaic Model

A
  • Phospholipid forms ‘fluid part’

- ‘mosaic ‘ made of protein, carbohydrate, lipid molecules, punctuate molecules

68
Q

Functions of Glycoproteins & Glycolipids

A
  • Some Proteins & Lipids have carbohydrate chains attached to them ( which are vital)
  • able to form Hydrogen bonds , STABILISING cell membrane
69
Q

Cell receptors

A
  • Active binding sites for communication molecules e.g drugs & hormones
  • starts chain reaction response
70
Q

Diffusion

A
  • passive movement of particles in liquids & gases from HIGH to LOW concentration down concentration gradient , through partially permeable membrane
71
Q

Active Transport

A
  • movement of ions/particles from LOW to HIGH concentration , AGAINST concentration gradient, through partially permeable membrane
  • contains carrier proteins in membrane, facilitating movement
72
Q

Factors effecting Active Transport

A
  • surface area of membrane

- number of carrier proteins in membrane

73
Q

Osmosis

A
  • net movement of water from DILUTE to Concentrated solution, through a partially permeable membrane
  • down concentration gradient
74
Q

Factors effecting Osmosis

A
  • lower water potential = slower rate of osmosis
  • thicker membrane= slower rate of osmosis
  • smaller surface area= slower rate of osmosis
75
Q

Mitosis

A

Interphase :
- cell prepares to divide, DNA replicated, 2 copies of every chromosome , organelles replicated,
Prophase:
- chromosome ‘COIL’ tighter , CENTRIOLES move to opposite POLES
- Microtubules form mitotic spindle between centrioles

76
Q

Mitosis

A

Metaphase:
- Chromosomes line in middle , chromosomes condense , attach to spindle fibres
Anaphase:
- Chromosomes break into 2 CHROMATIDS , sister chromatids separate
- spindle fibres CONTRACT & PULL chromatids to each pole

77
Q

Mitosis

A

Telephase :
- Chromatids condense , becoming Chromosomes ,Nuclear envelope form around chromosome , 2 nuclei form
Cytokinesis
- Cytoplasm split , 2 daughter cells form
- Cell cycle restarts

78
Q

Meiosis 1

A

Interphase A:
- Chromosomes replicate
Prophase A:
- Chromatids condense form DOUBLE ARMED chromosome ( sister chromatid)

79
Q

Meiosis 1

A

Metaphase A:
- Chromosomes with identical genes ( homologous pairs)
arrange in middle move to spindle fibres
Anaphase A:
- homologous chromosomes separate randomly , pull to opposite ends of spindle

80
Q

Meiosis 1

A

Telephase A:
- RANDOM combination of chromosomes pulled to each side of cell
Cytokinesis:
- Cell divides into 2 cells , 1 chromosome pair separate into each cell
Meiosis 1 produces - 2 genetically varied cells

81
Q

Meiosis 2

A

Prophase B:
- Chromatids condense again
Metaphase B:
- Chromosomes line up in middle

82
Q

Meiosis 2

A

Telephase B :
- Sister chromatids separate
Cytokinesis:
- Cell divides in 2 , 1 Chromosome pair separate into each cell
Meiosis 2 produces - 4 genetically Varied cells

83
Q

Comparing Meiosis & Mitosis

A

-Meiosis produces 4 genetically VARIED cells
, whereas Mitosis produces 3 genetically identical cells
- Meiosis produces HAPLOID cells ( half of parent cells : 23 chromosomes)
, whereas Mitosis produces DIPLOID cells ( same as parent cells : 46 chromosomes)
- Meiosis only produces Gametes
, whereas , Mitosis replicates EVERY body cell

84
Q

Types of Stem Cells

A

Totipotent :
- limited time during Embryonic development
- produces ANY type of body cell , most unspecialised
Pluripotent :
- Divides Unlimited amount of times, producing ANY cell
treats human disorders

85
Q

Types of Stem Cells

A 
Multipotent :
- found in animal 
- produces LIMITED amount of cells e.g Bone Marrow
Unipotent:
- found in animals
- Produces ONLY 1 type of cell
86
Q

Uses of stem cells benefits & disadvantages

A 
Sources: Adult stem,  Embryonic, IPS
Benefits:
- reduces Preventable deaths
- Treats conditions
Disadvantages:
- seen as unethical : ' depriving embryo of life'

A level (2 decks)

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