Loren's bio 3
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The basic unit of heredity
What are genes composed of?
Where are they located at?
What's an allele?
When a gene exists in more than one form the alternative forms are called alleles
What's a genotype?
the genetic makeup of an individual
The phenotype is?
the physical make up of a person....
A true breeding individual is....
if self crossed will only produce offspring with the same phenotype
Mendels 4 laws of inheritance...
- 1. genes exist in alternative forms (alleles)
- 2. organisms have two alleles for each trait, one from each parent
- 3. the two alleles segregate during meiosis.
- 4. if two alleles are different, only one will be fully expressed (dominant, recessive)
only one trait being studied in a particular cross
What's a test cross?
a homozygous recessive (dd) organism is crossed with an unknown dominant organism (DD, or Dd) to find out what the dominant organism really is.
When the parents differ in two different traits.
what is crossing over?
it exchanges information between chromosomes and may break the linkage of certain patterns
What's an example of codominance?
- ABO blood groups
- specifically AB blood (they're both dominant)
Sex linked chromosomes are located.....?
on the X and Y chromosomes
Do environmental factors affect gene expression?
- yes, the himalayan hare (dark fur)
- (drosophila have crooked wings in low temp)
What is nondisjunction?
- the failure of homologous chromosomes to separate properly during meiosis I
- the resulting zygote would have 3 copies or a single copy
What's a mutation?
a change in the genetic info of a cell, coded in the DNA
What genetic malfunction causes sickle cell anemia?
a substitution of valine (GUA or GUG) for glutamic acid (GAA or GAG)
CUT the PIE
Cytosine/ Urasil/ Thymine are all PYrimidines
Purines consist of ???
Adenine and Guanine
What are the stop codons?
What are the stops codons
What does RNA contain that DNA doesn't have?
- instead of Thymine
Is RNA usually single stranded?
- messenger RNA
- it is the complement of the DNA sequence (it has the copy of the DNA sequence but opposite or backwards, kinda like a mirror)
- it goes from the nucleus to the ribosomes where protein synthesis occurs
- transfer RNA
- found in the cytoplasm
- helps in the translation of mRNA's code into amino acids.
- helps bring amino acids to the ribosomes during protein synthesis
- it recognizes and snags mRNA and amino acids (attaches them)
- ribosomal RNA
- a structural component of ribosomes
- the most abundant, made in the nucleolus
when information on DNA is transcribed into a strand of mRNA which then leaves the nucleus
- the process whereby mRNA codons are translated into a sequence of amino acids
- in the cytoplasm
- There are two subunits. Like a sandwich
- they bind together during protein synthesis
Polypeptide synthesis has three stages...?
- 1. initiation
- 2. elongation
- 3. termination
Initiation of synthesis...
- ribosome binds to mRNA near 5' end.
- scans the mRNA til it gets to AUG
Elongation of synthesis....
hydrogen bonds form between mRNA codon and it's anti codon (the opposite complements of mRNA codon)
Termination of synthesis...
When one of the stop codons (UAA, UAG, UGA) arrives, they signal the ribosome to stop translation
Bacterial genomes have circular DNA rings called....
Episomes are plasmids that are capable of integration into thhe bacterial genome
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