A gene is a length of DNA, that codes for one (or more) polypeptides
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What does this mean of genes?
It means genes are a sequence of nucleotide bases. They are a unit of heredity
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What is the name for the culmination of genes in an organism? What is the total number of genes in humans?
A genome, there is approximately over 25,000 genes in the human genome
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Where are genes found ?
Each gene occupies a specific place or locus on the chromosome.
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List what genes code for :
Structural proteins: collagen and keratin. Haemoglobin, Immunoglobulins, cell surface receptors, antigens, actin and myosin in muscle cells, tubulin, channel proteins, electron carriers, enzymes.
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If Genes code for proteins, What else do they have control over?
Proteins make enzymes, therefore genes are involved in the control of all metabolic pathways and therefore synthesis of all non-protein molecules found in cells.
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What are the 3 properties of The Genetic Code
It is a triplet code, It is a Degenerate code, The code is partially transferable between organisms
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Discuss the triplet nature of the Genetic code
The Gentic code is a triplet code, A sequence of three nucleotide bases codes for one amnio acid, There are 4 Bases giving 64 possible combinations.
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Why is the Genetic code Degenerate ?
There are 64 triplet codes and only 20 amino acid. This means all amino acids have more than one code ( except for methionine) ( some codes also code for a stop at the end of the polypeptide chain)
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Where are proteins assembled?
In the cytoplasm of cells on ribosome.
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How does the genetic code get from the Nucleus to the Cyctoplasm's ribosome?
A copy of the gentic code is made called Messenger RNA. This can pass through the pores of the nuclear envelope into the cytoplasm.
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What is the name of the process by which mRNA is made?
Transcription
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Where does Transcripton occur ?
Cell Nucleus
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What is the role of tRNA?
Acts as an adaptor to bring specific amino acids to the ribosome and line it up in the correct poistion along the mRNA
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What shape describes tRNA?
A cloverleaf or hairpin, Formed by folding an RNA chain
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What is the role of Ribosomes?
Forms the structural framework by which, mRNA is held in place while tRNA brings amino acids for formation of proteins
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Describe Translation?
mRNA binds to ribosome. 6 bases are bound to small subunit and are exposed in larger subunit. tRNA complimentary to anticodon bonds to first 3 bases. 2nd tRNA binds to 2nd codon. Peptide bond forms <-> adjacent amino acids. Ribosome moves along mRNA.
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What stops the Amino acid chain from growing, during translation?
The stop codon at the end of the gene releases the gene and dissasociates the ribosomal subunits.
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Define mutation?
A structural change to genetic material either to a gene or to a chormosme
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Other cards in this set
Card 2
Front
What does this mean of genes?
Back
It means genes are a sequence of nucleotide bases. They are a unit of heredity
Card 3
Front
What is the name for the culmination of genes in an organism? What is the total number of genes in humans?
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