bio mock mock (2.3,2.4,2.5)

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  • Created by: charlie
  • Created on: 14-01-14 20:42

2.4 haemoglobin

  • pigment transports oxygen
  • globular protein with quaternary structure - (protein consists of 2 or more polypeptide chains) 
  • 4 polypeptide chains - each folded around an iron atom - (4 haem groups)
  • 2 alpha globins 2 beta globins 
  • oxygen + haemoglobin <=> oxyhaemoglobin 
  • 4O2 + Hb <=> HbO8

CO2 makes Hb give up O2 

  • respiring tissue -> CO2 -> red blood cells ->
  •  CO2 + H2O -(carbonic anhydrase)<=> H2CO3 ->
  • H2CO3 <=> H+ + HCO3-
  • H+ lowers pH (acidic) in Hb which lowers affinity for O2 

 

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2.4 haemoglobin (2)

different haemoglobins in different organisms

  • WORMS (tubifex) - Hb has much higher affinity for O2 than humans (Hb more O2 philic)
  • FETAL - Hb affinity is much higher than mothers -> 
  • different O2 levels so fetal Hb pulls O2 from mothers Hb 

Haemoglobin has an affinity (natural attraction) for oxygen (O2)

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2.4 carbohydrates

MONOMER- monosaccharides - (glucose, fructose)

POLYMER- polysaccharides - (starch, glycogen, cellulose) 

  • monomers exist as ISOMERS (same chem. formula but arrangement of atoms are different)

Isomers of glucose : 

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2.4 carbohydrates (2)

  • .
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2.4 plant cells

MICROFIBRILS -

  • parallel chains of cellulose cross-linked with H-bonds forming bundles of 60-70 molecules 
  • embedded in framework of other substances in pectins + 'glued' to cell wall by hemicelluloses (short chain glucose molecules)
  • arrangement determines shape of primary cell wall - how flexible to grow yet strong to hold force exerted by water

CELL WALL

YOUNG PLANT (primary cell wall): 

  • CELLULOSE - insoluble + doesnt affect water potential + very strong 
  • strong, permeable, flexible 

OLD PLANT (secondary cell wall):

  • impermeable - xylem tubes of cellulose + lignin (linving contents die) 
  • keep permanent shape + more strength 
  • impreganeted with lignin (cell wall )+ suberin (cork cells outer tree bark) + both waterproof
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2.4 plant cells (chloroplasts)

  • organelles containing all pigements, enzymes + other substances for photo. 
  • mainly in palisade cells 
  • large internal SA so as much chlorophyll as possible comes in contact with light 
  • flatterned shape enables rapid diffusion 
  • THYLAKOID - houses chlorophyll + sight of light dependent reactions 
  • GRANUM - thylakoids in stack giving larger SA 
  • STARCH GRAINS - excess carbs. from photo. 
  • STROMA - fluid contains enzymes using ATP from early photo to fix CO2 to sugar (light independent reaction)
  • DOUBLE MEMBRANE - permeable phospholipid bilayer  to O2, CO2, glucose, ions 
  • LIPID DROPLETS 
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2.4 plant cells (variation)

GUARD CELLS 

  • cell wall + lignin thickening on inside - holds place as water enters + cell becomes turgid
  • stoma opens 

XYLEM VESSELS 

  • lignin cell walls - causes cell death (hollow large SA) - very strong holding plant against water force

ROOT HAIR CELL 

  • large SA - no chloroplasts - pure cellulose (permeable to water + minerals)

PALISADE CELL

  • lots of chloroplasts - elongated - tube shape (fit max density of photosynthetic cells)
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2.3 genetic diversity

3 mechanisms reduce GD:

ARTUFICIAL SELECTION:

  • man decides which characteristics desirable in organism + breeds to inc. freq of features 
  • BREEDING - reduces variety + inc. faulty genes being expressed 
  • ETHICS - creating animals that have poor / reduced life quality 

FOUNDER EFFECT:

  • new population established by small number of individuals carrying only small fraction of original pop. genetic variation. (less allele frequency as mainland pop.)
  • carried at random to offshore island by natural forces (strong winds) 

GENETIC BOTTLENECKS 

  • large proportion of pop. killed prevented from reproducing, then recovers from just a few individuals. 
  • e.g. CHEETAHS - escaped extinction from ice age 10-20000 years ago so less variation from reproducing with small numbers - sensitive to disease, sperm abnormalities... 
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2.6 tissues, organs + cells

CELLS - unit of life, all living oranisms are made up of cells 

  • undifferentiated cells (no fixed purpose or function)
  • TOTIPOTENT - (can form any type of cell) - PLANT CELLS, ZYGOTE 
  • PLURIPOTENT - (several types of cells) - STEM CELLS 
  • Become differentiated by gene switching 
  • genes switched on/off determining which proteins are made- determining cell shape+ function

TISSUES - aggregation (collection) of cells performing a similar function 

  • nerve 
  • epithelial 
  • muscle 
  • conncetive 

ORGANS - aggregation of tissues performing a specific physiological function 

SYSTEMS - group of organs working together to acheive major physiological function 

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genetics test - DNA

DNA molecules 

  • DNA polymer - nucleotides continually repeat 
  • diagram of DNA - 
  • bases -                   adenine, thymine, cytosine, guanine 
  • triplet code-           (sequence of 3 bases coding for A.A)
  • introns-                   parts of a gene that arent expressed 
  • exons-                    parts of  a gene that are expressed 
  • multiple repeats -   non coding DNA 

SEMI CONSERVATIVE REPLICATION 

  • strang containing orginal DNA is used as a TEMPLATE and new strand therefore always contains half orginal parent DNA. 

STRUCTURE ALLOWS ACCURATE REPLICATION 

  • 2 stands, weak H bonds between bases, one strand unzips easily, free nucleotides join on, forms 2 idnetical copies of DNA with half parental and half new 
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genetics test - twins

identical (monozygotic) 

  • exactly same genotype - any differences due to ENVIRONMENTAL factors (upbringing)
  • random gene expression creates differences - patterns of moles/ freckles is different 

non idnetical (dizygotic) 

  • different genes but largely the same environment (though never exactly the same)
  • any differences are largely GENETIC 

difficult to draw conclusions 

  • few subjects to study - chance plays large part in contributing to differences between samples
  • more reliable = random sampling from large number 
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genetics test - labelling meiosis chromosomes

chromosomes at the start 

distribution of chromosomes to 4 gametes 

(fewer gametes have Ef + eF - most have EF + ef  because crossing over is infrequent between closer genes)

chromosomes on spindle 

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genetics test - cancer + mutations

  • cancerous tumour formed by uncontrolled mitotic division 
  • results in mass of normal cells with inadequate blood supply 
  • drugs developed killing cells in low oxygen environment 
  • this kills cancer cells as blood supply is insufficient enough in reaching the demand of the cancerous cells 

mutations 

  • change in primary structure 
  • change in H bonds 
  • charge in tertiary structure of enzyme 
  • change in active site shape meaning no enzyme-substrate complexes can form 

can spread due to FOUNDER EFFECT 

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genetics test - meiosis + mitosis

Meiosis 

  • PROP 1 - (1st) diploid cells 2N - mat +pat (pairing) twist - bivalent (last) cross + lie- chiasma
  • MET 1 - spindles to centrioles + pull bivalents to equator (INDEPENDENT ASSORTEMENT)
  • ANA 1 - spindles shorten - opposite poles 
  • TELO 1 - spindles go + nuclear envelope around haploid chromo
  • INTER - chromo decondense (CYTO may occur) centrioles replicate 
  • PROP 2 - centrioles separate forming spindles 
  • MET 2 - chromo attached to spindle equator by centromeres
  • ANA 2 - spindles shorten - opposite poles 
  • TELO 2 - nuclear envelope - 4 haploid cells 

mitosis 

  • INTER - DNA replicates 
  • PROP - chromo condense, centrioles appear + spindle fibres attach to centomeres 
  • MET - moves to equator 
  • ANA - spindles shorten - opposite ends 
  • TELO - chromatids (now chromo) reach poles, nuclea membrane, + unwinds 
  • (CYTO) - division of cytoplasm between 2 new nuclei 
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