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28 Cards in this Set
- Front
- Back
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What three components make up a nucleotide? |
Phosphate molecule, pentose sugar and nitrogenous base |
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How do polynucleotides form and what forms? |
They form from condensation reactions when the phosphate group at the 5th carbon atom forms a covalent bond with the OH group at the 3rd carbon atom called a phosphodiester bond |
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What pentose sugar is used in DNA and RNA? |
Deoxyribose sugar and ribose sugar |
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What is a purine base and what are the bases? |
The larger bases with two carbon ring structures Guanine and adenine |
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What is a pyrimidine base and what bases are there? |
The smaller base with one carbon ring Thymine, cytosine and uracil |
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What is the structure of the double helix? |
The antiparallel strands with a phosphate group (5') and OH group (3') at each end are held together by hydrogen bonds between nitrogenous bases (A to T and G to C) |
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Why is complementary base pairing important? |
It ensures that there are correct amount of bases. It also allows the reformation of H bonds and reduces occurrence of mutations |
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What happens to RNA once it has been made redundant? |
The single-stranded nucleic acid is hydrolysed in the cytoplasm and the RNA nucleotides are released and reused |
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What does semi conservative replication mean? |
DNA replication that results in one old and New Strand in each daughter DNA molecule and 1 stand acted as template |
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What are the steps for DNA replication? |
1. DNA helicase unwinds the two strands 2. Both strands act as templates for the formation of new strand and free nucleotides are attracted to the complementary bases 3. Hydrogen bonds between bases reform and DNA polymerase joins together the nucleotides to reform phosphodiester bonds and sugar-phosphate backbone |
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What is a gene? |
A section of DNA that contains the complete sequence of bases (codon) to code for a protein |
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What's the deal with lagging and leading Strands? |
DNA polymerase only travels from 3' to 5', so leading strand can be replicated continuously, the lagging Strand has to be replicated in the opposite direction in short sections called okazaki fragments |
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What is a codon/ triplet code? |
A 3 base sequence of DNA or RNA that codes for an amino acid |
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What three main activities do cells need energy for and what are some examples? |
Synthesis e.g. protein synthesis Transport e.g. active transport of minerals in roots Movement e.g. flagella |
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What is the structure of ATP and what is it an example of? |
It is a type of nucleotide that has three phosphates and adenine molecule bonded to a ribose sugar |
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Name of reaction and chemical equation of ATP releasing energy? |
Hydrolysis: ATP +H2O -> ADP + Pi + energy |
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What is the process when energy from respiration is used to reattach phosphate groups to ADP? |
Phosphorylation |
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What are 5 properties of ATP? |
Small (can easily move out of cells) Water-soluble Easily regenerated Releases energy in small quantities Bonds between phosphates releases intermediate energy |
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What is the name for the one Strand that contains code for the protein? |
Sense Strand |
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What is the name for the complimentary copy of the sense Strand but doesn't code for the protein? |
Antisense /template Strand |
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Describe the method of transcription... |
1. DNA helicase separates the two strands of DNA 2. Free RNA nucleotides start complementary base pairing with the template strand (uracil binds to adenine) until the end of the gene to form mRNA 3. mRNA leaves the nucleus and DNA polymerase binds the DNA bases back together |
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Describe the method of translation... |
1.mRNA binds to a ribosome at the start codon 2. tRNA have complementary anticodons at one end and an amino acid at the other, anticondons bind complementary codons 3. Another tRNA binds to the mRNA and the two amino acids form peptide Bond when they are close together (catalysed by peptidyl transferase) forming the primary structure of the protein 4. tRNA molecules are released when amino acids Bond and the chain moves along until the end codon |
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What happens straight after a protein is formed? |
It folds into it's secondary/ tertiary structure and protein may undergo further modifications at the Golgi apparatus |
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What do free ribosomes in the cell make? |
Proteins that are to be used within the cell |
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How did introns end up in our DNA? |
There were originally functional genes but viruses may have infect them changing the base sequence and changing it so they no longer code for useful proteins |
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How many H bonds form between AT and GC? |
2 and 3 |
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What is the biuret test and how is it carried out? |
It is used to detect the presence of peptide bonds Peptide bonds form violet colours with copper ions in an alkaline solution of NaOH and Cu(II)SO4 |
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What does degenerate code mean? |
When amino acids can be coded for by more than one codon |
