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
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”
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
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
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
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
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
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
9
Q
Microtubules
A
- MAINTAIN SHAPE of cell
- RESIST COMPRESSIVE FORCE
10
Q
Magnification
A
- ENLARGING an object in appearance
image size= how BIG object appears (mm)
actual size= in micrometers (μm)
11
Q
Calculating Magnification and Conversion Units
A
magnification = image size / actual size 1mm= 1000μm
12
Q
Resolution
A
- the ability to DISTINGUISH between 2 separate objects with CLARITY
13
Q
Importance of Water
A
- Reactant in cellular reactions e.g (Photosynthesis & Hydrolysis)
- provides STRUCTURAL Support in cells
- Keep organisms COOL
14
Q
Properties of Water
A
- Metabolic importance
- high Specific Heat Capacity
- high latent heat
- cohesive
- solvent uses
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 ‘
16
Q
Monomers
A
SINGLE sub unit of life e.g. amino acid , nucleotide , monosaccharides
17
Q
Polymers
A
formed from COMBINING MONOMERS via covalent bonding
- complex monomers e.g Proteins, DNA , Starch
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’
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)
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)
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
22
Q
Features of Starch
A
- DO NOT change water potential on cell = INSOLUBLE in water
- Made of AMYLOPECTIN & AMYLASE
23
Q
Amylopectin
A
- Highly BRANCHED chain of Alpha- Glucose Monomers
- Branched Structure =Enzymes can access Glycosidic bonds & glucose quickly released
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
25
Formation of Fatty Acids
- 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
26
Structure of Fatty acids
- LONG ' Tails' made from hydrocarbon chains 4-36 Carbon atoms
- hydrocarbon 'tail' varies
- glycerol binds to 'central carbon atom; on FATTY ACID
27
Structure of Saturated fat
- Carbon atoms not joined via double bond
| - number of hydrogen atoms attached to carbon skeleton is MAXIMISED
28
function of saturated fat
-SOLID at room temp
- increases risk of Cardiovascular disease in humans
sources of saturated fat :
- cream , cheese , butter
29
structure of polypeptides (proteins)
- made of amino acids
- dipeptides formed via CONDENSATION of 2 amino acids
- Polypeptides formed via CONDENSATION of Many amino acids
30
Structure of Amino Acids
- 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
31
Amino acids
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
32
amino acids
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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
Importance of Amino acid sequence
- 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
34
Tertiary structure of Protein
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
35
Ionic bonds
-charged amino acids have oppositely charged ions in side chain
forming strong ionic bonds with other charged amino acids
- RARE
36
Disulfide bridges and hydrogen bonds
- S-S covalent bond within protein containing CYS amino acid
- Hydrogen bonds form between amino acids
weak & strengthen when there are MANY
37
Structure of Globular Proteins
- 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
Functions of Globular proteins
- messengers
- enzymes
- structural protein
example: haemoglobin , insulin & DNA
39
inorganic ions- Cations
ions in living organisms - obtained via nutrition
Cytoplasm& body fluids MAINTAIN optimum levels
- some ions have higher concentrations , lower concentration of toxic ions
40
inorganic ion names
- 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
Test for Lipids & Protein
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
Test for Sugars& Starch - Reducing sugars
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
Test for Sugars & Starch - Non Reducing sugars
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
Colorimetry
- 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
Biosensors
- made of biological elements & a physiochemical detector
- biological component is sensitive e.g. microorganisms , enzymes
- biosensors produce electrical signals from BIOLOGICAL RESPONSES
46
Chromotography
- separates substances based on their INTERACTION to mobile & stationary phase
mobile phase= solvent
stationary phase= solid support
47
chromotography
- 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
DNA
```
- DEOXYRIBONUCLEIC ACID
contains all genetic info
codes for proteins
in Eukaryotes= DNA is in nucleus/chloroplasts/mitochondria
Prokaryotes= DNA in form of plasmid
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49
RNA
synethises proteins
| ribosomes formed from RNA & Proteins
50
Role of mRNA
DNA uses messenger RNA for transfer of genetic info to cells
| mRNA moves out of nucleus to ribosomes to make proteins
51
DNA structure
- made of 2 polynucleotide chains (double helix)
- Sugar & Phosphate OUTSIDE helix
- Nitrogen base INSIDE helix
- Hydrogen bonds HOLD base pairs
52
RNA Structure
- SHORT polynucleotide chains ( 1 chain)
| - made of RIBONUClEOTIDE linked by Phosphodiester bond
53
Component of ATP
- ADENINE - Nitrogenous bonds
- RIBOSE- 5 carbohydrate- sugar
- 3 PHOSPHATE groups
54
Function of ATP
- Small/ simple molecule
| - ATP used to POWER ENERGY for cellular reactions
55
DNA replication
- 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
Transcription
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
Transcription
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
Transcription
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
Transcription
7) mRNA
- completed mRNA leaves nucleus to reach cytoplasm
- mRNA used in translation then SYTHESISED
60
Enzyme Structure & Function
- Enzymes catalyse reactions
61
Factors affecting Enzyme action
- 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
Coenzyme
- small molecules with increase activity of enzyme
- bind to enzyme, causes conformational change
- inorganic/organic molecules
- e.g Vitamins
63
Prosthetic groups
- inorganic molecules
- permanently bind to enzymes - forming part of structure
- increasing rate of enzyme activity
64
Structure of Phosphlipids
- 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
Function of Plasma membrane
- defines border of cells
| - partially permeable
66
Structure of Cholesterol
- Lipid sitting with Phospholipid in CORE of membrane
- Not found in Bacterial cell membrane
- rigid
- Maintains shape of cell
67
Fluid Mosaic Model
- Phospholipid forms 'fluid part'
| - 'mosaic ' made of protein, carbohydrate, lipid molecules, punctuate molecules
68
Functions of Glycoproteins & Glycolipids
- Some Proteins & Lipids have carbohydrate chains attached to them ( which are vital)
- able to form Hydrogen bonds , STABILISING cell membrane
69
Cell receptors
- Active binding sites for communication molecules e.g drugs & hormones
- starts chain reaction response
70
Diffusion
- passive movement of particles in liquids & gases from HIGH to LOW concentration down concentration gradient , through partially permeable membrane
71
Active Transport
- movement of ions/particles from LOW to HIGH concentration , AGAINST concentration gradient, through partially permeable membrane
- contains carrier proteins in membrane, facilitating movement
72
Factors effecting Active Transport
- surface area of membrane
| - number of carrier proteins in membrane
73
Osmosis
- net movement of water from DILUTE to Concentrated solution, through a partially permeable membrane
- down concentration gradient
74
Factors effecting Osmosis
- lower water potential = slower rate of osmosis
- thicker membrane= slower rate of osmosis
- smaller surface area= slower rate of osmosis
75
Mitosis
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
Mitosis
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
Mitosis
Telephase :
- Chromatids condense , becoming Chromosomes ,Nuclear envelope form around chromosome , 2 nuclei form
Cytokinesis
- Cytoplasm split , 2 daughter cells form
- Cell cycle restarts
78
Meiosis 1
Interphase A:
- Chromosomes replicate
Prophase A:
- Chromatids condense form DOUBLE ARMED chromosome ( sister chromatid)
79
Meiosis 1
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
Meiosis 1
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
Meiosis 2
Prophase B:
- Chromatids condense again
Metaphase B:
- Chromosomes line up in middle
82
Meiosis 2
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
Comparing Meiosis & Mitosis
-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
Types of Stem Cells
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
Types of Stem Cells
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Multipotent :
- found in animal
- produces LIMITED amount of cells e.g Bone Marrow
Unipotent:
- found in animals
- Produces ONLY 1 type of cell
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86
Uses of stem cells benefits & disadvantages
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Sources: Adult stem, Embryonic, IPS
Benefits:
- reduces Preventable deaths
- Treats conditions
Disadvantages:
- seen as unethical : ' depriving embryo of life'
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