Genetics Lecture 1
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31 terms
Terms | Definitions |
|---|---|
 definition of the human genome | all the DNA that a person possesses, stored on 23 chromosome pairs |
| how many genes does the human genome contain? | about 30,000 |
| what does 1 gene code for? | 1 protein |
| how do genes become proteins? | cellular machinery makes a copy of the DNA called mRNA, the mRNA is then used as a template for making a protein |
| what is the relationship between DNA and chromosomes | 1 chromosome = 1 DNA molecule |
| where are chromosomes located? | in the nucleus |
| what are the two types of chromosomes humans have? | autosomal, sex-determining |
| how many pairs of autosomal and sex-determining chromosomes do humans normally have? | 22 autosomal, 1 sex-determining |
| outline the composition of the DNA molecule | sugar phosphate backbone, nitrogenous base-pair rungs |
| give the bonding pairs of nitrogenous bases | A-T, G-C |
| name the 4 nitrogenous bases in DNA | adenine, thymine, guanine, cytosine |
| name the 4 nitrogenous bases in RNA | adenine, uracil, guanine, cytosine |
| how do the sugar phosphate chains become arranged in a helix shape? | the base pairs are held together by hydrogen bonds |
| do purines link to purines or pyrimidines in DNA? | purines link to pyrimidines |
| name the two purines in DNA | A,G |
| name the two pyrimidines in DNA | T,C |
| components of a typical gene | 5' end, promoter region, alternating exon and intron regions, 3' end |
| how does the 3rd position wobble arise? | arises from the redundancy in the genetic code, whereby multiple 3-letter combinations code for the same amino acid, therefore in some cases a mutation in the 3rd position won't affect the coding |
| how many start codons are there? | 1 |
| how many stop codons are there? | 3 |
| define transcription | production of mRNA; the transcribing of the DNA sequence into RNA |
| define translation | reading of mRNA; the translating of the mRNA into a string of amino acids to make a protein |
| where does transcription occur | in the nucleus |
| what is the intermediate step between transcription and translation? | RNA processing |
| where does RNA processing take place? | in the nucleus |
| where does translation occur? | at the ribosome |
| what are the steps in transcription | 1. initiation - the catalyst RNA polymerase binds to promoter sequence and 'opens' the DNA 2. elongation - RNA polymerase advances 3' to 5' creating a complementary strand of RNA 3. termination - RNA polymerase reaches a stop codon and release completed RNA. Dissociates from DNA |
| what are the steps in RNA processing | 1. each end of the mRNA is MODIFIED 2. internal sequences of the mRNA are SPLICED (exons linked together, introns spliced out) |
| what are the steps in translation | 1. ribosome traverses mRNA 2. tRNAs are added that code for specific amino acids 3. protein is assembled by adding peptide bonds to the growing amino acid chain |
| outline the central dogma of genetics | information flow goes in one direction only: DNA --> mRNA --> protein |
| implication of the central dogma for understanding genetic diseases | a mutation is only an inherited mutation if it exists at the DNA level |
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