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DNA
· Deoxyribose Nucleic acid ­ information caring molecule, carries genetic code
· Nucleotide deoxyribose, phosphate group, base (nitrogen)- adenine, guanine, thymine ,cytosine
· Condensation polynucleotide ­ sugar phosphate backbone
Structure related to function:
1.Carries code in bases ­ triplet/ unzip P synthesis/ strong backbone = stable/ large
carry info
2.Can replicate prior to cell division
DNA Helicase unzips complimentary base pairing with fee nucleotides to
exposed bases backbone formed. DNA Polymerase joins the bases.
·Semi conservative ­ conserves half old DNA in each new molecule (1new, 1old)
Genetic code
Gene ­ section DNA - coded info sequence of AA polypeptide protein determining development
Genetic code ­ relationship between base sequence in DNA and sequence of AA in protein
Triplet (3base=1code), degenerate (some have +1code + stop codons), non overlapping (1st doesn't
dictate next), universal all organisms use it.
Mutations
Change in DNA sequence different protein
·Different AA altered tertiary structure enzyme ineffective (metabolic pathway, end product = no
·Beneficial allele formed better survival
·Can cause cancer ­ spread metastasis. Treated by chemo (Spindle form inhibited), surgery,
radiation…read more

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Cell division
The cell cycle
Interphase ­ (G1) growth, protein synthesis, (S) DNA replication, (G2) grow and divide
Nuclear division ­ nucleus divides
Cytokinesis ­ cytoplasm divided form new cell
Mitosis
Produces 2 genetically identical daughter cells ­ differentiation (specialisation) growth + repair asexual
diploid
Sister chromatids…read more

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Meiosis
Produces 4 genetically different
gametes haploid
Variation
Crossing over
Breakage +rejoining of DNA between
non-sister chromatids
recombination of genetic material.
Independent segregation
Homologous chromosomes orientate
randomly on equator during
metaphase 1 separate
independently different gene
combinations.
Mutations during replication…read more

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Inheritance
Intron ­ non-coding region of a gene not expressed
Exon ­ expressed region of a gene
Chromosomes
Molecule of DNA associated with protein ­ numbers vary for species (humans ­ 46, 23pairs)
Eukaryotic ­ large, linear DNA. Each choromo at fixed position. Has introns
Prokaryote ­ small, circular. No protein. No intorns
Variation
Intra(between), Inter(within) specific
Causes: genetic (crossing over etc) / environmental
Twin studies - determine if variation environmental or genetic. ID same geno, enviro/non different
geno, same enviro
Genetic Diversity
Selective breeding ­ beneficial alleles selected up yield/ reduced diversity, up risk of recessive allele
Founder Effect ­ small pop colonise new area (small %alleles) less diversity. inbreeding, no variation
Genetic Bottleneck ­ pop suffers dramatic drop disaster survivor (small variety) inbreeding…read more

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Variety of life
Haemoglobin
· 4polychains containing haem load + unload O2 at various partial pressures.
· Has high affinity when pp high (lungs), low when pp is low (tissue)
· During respiration CO2 carboxylic acid, denatures enzyme readily release O2 Bohr Shift R
· In low O2, high metabolic rate, foetal + myoglobin to left
Polysaccharides
Starch ­ polymer alpha glucose, stored as grains in cytoplasm +
chloroplasts. High in storage organsStarch ­ polymer alpha glucose,
stored as grains in cytoplasm + chloroplasts. High in storage organs
Glycogen ­ carb energy store in animals cytoplasm as granules. High
in liver + muscle (branched)
Adaption: easily hydrolysed/ large (no osmotic effect), compact shape
store lots
Cellulose ­ polymer beta glucose, structural support in cell wall to
prevent osmotic damage. (chained)
Adaption: large, insoluble/ microfibrils ­ cellulose fibres high tensile
strength (hydrated gaps apoplast)
Plant structures
Chloroplasts ­ found in palisade, to photosynthesise. Contain stroma
(enzymes, sugar, starch), Granum/thylakoid membranes ­ chlorophyll
filled structures
Adaption: biconcave large SA/ stroma stuff needed/ thylakoid
membrane light absorbing pigment
Xylem ­ transport water + ions, long, tubular strengthened and protected by Lignin (woody, waterproof)
End walls disintergrate continous flow. Ligning pitted sidewards movement.…read more

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