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62 Cards in this Set
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- Back
- 3rd side (hint)
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Genetics |
The science of heredity |
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Genes |
Segments of DNA that code for functional products (usually proteins) |
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Genome |
All genetic information in the cell Carried on chromosomes, which are primarily made of DNA |
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DNA |
deoxyribonucleic acid |
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RNA |
Ribonucleic acid |
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Nucleotides |
The building blocks of DNA |
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What do nucleotides consist of? |
Phosphate groups Pentose sugar Nitrogenous base (nucleobase) |
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Structure of DNA |
- double stranded helix - polymer of nucleotides - complementary base pairings held together by hydrogen bonds |
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Number of hydrogen bonds between A - T? |
2 |
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Number of hydrogen bonds between C - G? |
3 (stronger) |
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What is the name of the sugar with numbered carbons in DNA? |
Deoxyribose |
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How are the carbons in deoxyribose arranged in DNA? |
The 5' carbon is attached to the phosphate group The 3' carbon is attached to an alcohol group (OH) The two strands of DNA are arranged anti-parallel to each other |
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Anti-parallel |
One strand of DNA is oriented 5'-3' while the other is oriented 3'-5' |
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How do bacteria replicate? |
Binary fission |
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Bacterial Chromosome |
Bacteria have 1 closed circular chromosome ccDNA |
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How long is the E. coli chromosome? How much of the cell volume does it take up? |
- 4 million base pairs - 1mm long - 1000x longer than the cell - 10% of the cell volume |
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Why does E.coli chromosome take up so little of the cell volume? |
Supercoiling |
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What relaxes supercoiled E.coli chromosome? |
The enzyme DNA gyrase |
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Where does DNA replication occur? |
At the replication fork |
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How are new strands added in DNA replication? |
In the 5' to 3' direction |
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What unwinds DNA for replication? |
Helicase |
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What are the two strands of DNA? |
Leading strand Lagging strand |
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Replication of the leading strand |
- RNA primase adds RNA primer to start - DNA strand synthesized continuously - Polymerized by DNA polymerase - Semiconservative replication |
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Polymerized |
The addition of complimentary bases to the parental strand |
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Semiconservative replication |
New strands of DNA are made of one old strand and one new |
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Replication of the lagging strand |
- DNA synthesis is discontinuous, being added in Okazaki fragments |
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What enzymes are required for replication of the lagging strand? |
- RNA primase - DNA polymerase - DNA ligase |
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RNA primase |
Makes RNA primer |
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DNA polymerase |
- Extends primer - digests RNA and replaces it with DNA |
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DNA ligase |
Seals the nicks between Okazaki fragments |
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What type of replication does E.coli go through? |
Bidirectional replication |
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Bidirectional replication |
Involves 2 replication forks which both start at the Origin of replication and finish by meeting each other at Termination site |
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Central dogma of molecular genetics |
DNA => transcription => RNA => translation => Protein |
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Transcription |
Re-writing from DNA to RNA |
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Translation |
Turning RNA into final product (protein) |
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Differences between DNA and RNA |
1. RNA = single stranded 2. RNA's sugar is ribose, DNA's sugar is deoxyribose 3. In RNA, U binds with A. In DNA, T binds with A |
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Types of RNA |
1. mRNA 2. rRNA 3. tRNA |
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mRNA |
- Messenger RNA - contains codons - is the blueprint for protein |
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rRNA |
- ribosomal RNA - Make up ribosomes |
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What type of ribosomes are found in bacteria? |
70S |
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tRNA |
- transfer ribosomes - transfer amino acids to the ribosomes for protein synthesis - Ensures the correct amino acid is brought into the ribosome to add on to the chain - contain anticodons |
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Anti codons |
Complementary to codons found in mRNA Found in tRNA |
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In what direction does transcription occur? |
5' to 3' |
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Describe the process of transcription |
- One DNA strand is used as a template to form a complimentary strand of mRNA - RNA polymerase recognizes and binds to the promoter site - The promoter directs RNA polymerase where to transcribe but is not transcribed itself - RNA polymerase synthesizes mRNA until it reaches the terminator site - RNA polymerase leaves the DNA strand and mRNA is released |
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Terminator site |
Marks the end of the DNA |
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Nucleotide triplet code for amino acids |
3 nucleotides code for one amino acid |
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Codons |
Three bases that code for a particular amino acid |
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How many different amino acids are incorporated into proteins? |
20 |
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How many base codes are found in a codon? |
3 |
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How many potential bases exist? |
4 (UAGC) |
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How many possible combinations of bases exist? |
64 |
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List 2 characteristics of genetic code |
1. Degenerative 2. Universal |
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Degenerative |
Repetitive - different codons code for the same amino acid |
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Stop codons |
Codons that terminate translation AKA nonsense codons |
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How many stop codons are there? |
3 |
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Translation |
The process of making a protein from an mRNA template |
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Steps of translation |
1. Attachment 2. Initiation 3. Elongation 4. Termination |
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Attachment |
- mRNA attaches to the ribosomes at the 5' end - small and large subunit come together |
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Initiation |
Begins when ribosome hits start codon Ribosome can hold 2 tRNAs |
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P site |
In the middle of the ribosome Holds the growing polypeptide chain |
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Elongation |
- New amino acids are added at the A site as peptide bonds are formed and the polypeptide chain gets longer - Old tRNAs are pushed to the E site where they are ejected |
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Termination |
- Translation of protein is completed when stop codon is reached - the release factor comes in and the complex falls apart, releasing the polypeptide chain (which eventually folds into a mature protein). |
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