8/8/2019 Biology Test Study Sheet
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Biology Test Study Sheet
Worksheets:Punnet Diagram Practice: Wholeworksheet 1;Pedigree
Worksheets: 2 nd Workbook,
pp. 1-5, 13-23.Recombination and Locus: pp. 10-12
Stuff that we learnt last term that we ve already forgotten:
DNA (Deoxyribonucleic Acid) is made up of subunits
callednucleotides. Chargratt figured out that the nitrogen
bases
Guanine matches with Cytosine, and Thymine matcheswith Adenine.
Diagram below summarises therelationships between DNA, mRNA and the
actual proteins.Don t forget that in RNA, Thymine becomes
Uracil.
Transcription is when a copy is made of the original DNA,and
translation is when the messenger RNA is changed intoa useable
protein by a ribosome in the cell. This proteinthen changes from a
polypeptide chain into an enzyme.
Handy Stuff RNA = Single strandedDNA = Double strandedIntron =
Non-coding DNA sequence,which is transcribed, but needs to
beremoved before translation.Exon = Pieces of DNA that are
actuallytranscribed and translated intoprotein, the useful
bits.Regulating Gene Expression = thepresence or absence of
repressorproteins that can stop translation.
Types of MutationsPoint Shift Mutations:
1. Silent Mutation: Substitution of a base, butwith no change to
amino acid.
2. Nonsense Mutation: Creates a Stop codon toprematurely end
amino acid.
3. Substitution Mutation: Substitution of a basesuch that a new
amino acid is inserted.
4. Frame Shift Mutation: Inserting or deletingbases to change
the reading of the threebases. It changes all or most of the
aminoacid after mutation.
Block Change: Several base changes.
Molecular Tools: (Could be on IB Test?)(pp456 in txtbk)
1. PCR (Polymerase Chain Reaction):Magnifying several repeat
copies of one small piece of DNA. Heatingseparates DNA, cooling
brings in newnucleotides.
2. Electrophoresis: Using electricity toseparate out fragments
of DNA. ShortDNA Longest gradient; Long DNA Shortest Gradient.
3. Restriction Enzymes: Cut DNA atspecific bases. Either Blunt
or Sticky.Whalan gave us a few sheets and moarnotes on this, so see
nuther box aboutthem.
4. Ligase Enzymes: These join DNA.5. DNA Probes: Short pieces of
DNA with
a marker attached, with fluorescent orradiation chemical, so one
can visually
identify pieces of DNA required.6. Automated Sequences
Synthesiser:
Adds a base to the required sequence.I have a hunch that if this
stuff i s on the test,Lynch will put in a tricky one in the IB
section.All these tools together are used to perform afunction or
make something, such as antibioticresistant enes to insert into
bacteria to make
Restriction EnzymesThese are naturally used by our cells to cut
upinvading viruses to inactivate them.Sticky End: DNA cut in such a
way is able to be joinedto other exposed end fragment of DNA with
matchingsticky ends.Blunt End: DNA cut in such a way is able to be
joinedto any other blunt end fragment, but tends to benonspecific
because there are no sticky ends asrecognition sites.
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Phenotype: Expression of a gene. This is amixture of your
genotype and the environment.Genotypes: Are the symbols. (Tt, tt,
TT)Phenotypes: The characteristic. (Red hair)-Variation can be
continuous, small variationbetween height, weight, skin colour,
etc.- Variation can be discontinuous, one or the
other. Eg. Genetic diseases, etc.
Intermediate Inheritance:Incomplete: In the heterozygous
individual, thealleles mix together. (One allele is not
dominant)eg. R = Red; W= White. RW = PinkCo-dominant: Both
expressed. Eg. RW = Roan, redand white hairs are present.Lethal
Genes: One genotype combination dies.
Multiple Alleles: Like blood types. Eg. (IA
IB
)Dihybrid: Where two traits areexpressed/inherited together.Back
crossing = Crossing with the double recessiveto test genotype
pedigree.Ratios
Dominant/Recessive = 3:1Incomplete = 1:2:1
Lethal = 2:1Dihybrid = 9:3:3:1
Dihybrid Linkage = 1:1OR 1: tiny : tiny : 1
Sex Linked GenesWhere genes are located on the X or Ychromosome.
(Boys are XY, Girls are XX)Sex Linked Recessive: Mothers pass to
sons.Sex linked Dominant: Fathers pass to daughters.
PedigreesDominant: One or more parents will hold gene. Atleast
half of offspring will hold gene. (Punnetsquares!)
Recessive: May skip generations, fromheterozygous parents. Trait
may be masked bydominance (eg. Skin colour) At least one quarter of
offspring will hold trait if parents are heterozygous.
Sex-Linked Recessive: Mothers pass to sons and
only sons. If a son is born that does not hold thespecific
characteristic, it cannot be X linkedrecessive.
Don t forget that pedigrees like the one below canbe recessive
or dominant... DON T BE FOOLED
Linked Genes The Locus
The Locus is the percentagedistance from one end of
thechromosome to another. Thefurther away a linked characteristicis
from another, the more likely itis to cross over. This
characteristicis then able to be shown inconjunction with
anothercharacteristic on a differentchromosome it wasn t able
to
before. See example picture
IB Basics RefresherHypothesis writing: The (insert object of
experiment) will (reaction anticipated) because
(explanation). Eg.Rainbow trout suffer more lice in low
water
conditions because there is less oxygen in thewater.Aim Writing:
To demonstrate the effects of (Insert variable here) on (insert
object here).Eg. Aim: To demonstrate the linkage betweensleeping in
class and depression.I think that s all she ll ask us to do on the
actualIB exam with regards to report writing.
