Intro to Genetics Flashcards
What does DNA stand for?
deoxyribonucleic acid
Define DNA
like a blueprint of information to make an organism
How does DNA control activities?
providing instructions to make proteins
Nucleotide is made of three smaller units. What are they?
- Deoxyribose - a sugar
- phosphate group
- one of four nitrogenous bases
What are the four nitrogenous bases?
Adenine (A), guanine(G), thymine(T) and cytosine(C)
Which nitrogenous bases are double ringed?
adenine and guanine
Which nitrogenous bases are double ringed?
thymine and cytosine
Adenine always pairs with…
Thymine
Guanine always pairs with…
Cytosine
What are the rings for pairs?
pairs always include one double ring and one single ring
A Nucleotide
the basic building block of nucleic acids (RNA and DNA) - the ACTG
What happens to DNA during mitosis?
it is copied and passed onto new cells
How is DNA described as it runs in opposite directions?
anti-parallel
What kind of end do you need to have to add to DNA
3’
purines
nucleotides with double ringed structures
Nucleotides can be either____ or _____
purines or pyrimidines
pyrimidine
nucleotides with a single ring structure
A Giant - A,G
mnemonic device to remember the purines, adenine and guanine
CuTe - C,T
mnemonic device to remember the pyrimidines, cytosine and thymine
What is the structure of DNA, describe it.
The structure of DNA is a double helix - where two chains of nucleotides run in opposite directions and join in the middle
Why can you determine the sequence of DNA on the second strand?
Because DNA is double-stranded if you know the seqence on one strand you can determine the sequence of the other strand, based on the nucleotide pairs
RNA
ribonucleic acid
What is another nucleic acid found in cells that is similar to DNA?
RNA
What is RNA made of?
nucleotides
RNA is made of nucleotides consisting of three parts….
phosphate group, sugar (ribose) and a nitrogenous base
What are the 4 nitrogenous bases of RNA
- same: adenine, guanine and cytosine
- different: uracil instead of thymine
How is RNA shaped?
Rna is a single-stranded helix,
What does Uracil pair with?
adenine
What does DNA make?
protein
What are proteins?
proteins are complex molecules with unique three-dimensional shapes
What are proteins made out of?
a string of amino acids
How many different amino acids are there?
20
How does DNA relate to the amino acids.
DNA contains the instructions to put the amino acids in the correct order.
What is the basic idea of transcription and translation?
It is the process of making genes
How does RNA relate to DNA and proteins?
RNA is the intermediate between genes on DNA and the proteins they code for
Define transcription
the process of making RNA using DNA (DNA ro mRNA)
what does mRNA stand for?
messenger RNA
Why is mRNA called what it is?
because it can leave the nucleus
What is translation?
translation is the production of polypeptides which occurs using mRNA (mRNA to protein)
Where does translation occur?
The ribosomes
Where are the instructions for assembling amino acids encoded?
They are encoded into DNA
how many nucleotide bases are there?
4
what is a triplet code used for?
A triplet code is used meaning three nucleotides in row code for one amino acid
what are codons?
the mRNA base triplets
what direction are codons read in?
5’ to 3’ direction
what information does each codon provide?
it specifies the amino acid to be placed at the corresponding position along the polypeptide
What enzyme is used to make mRNA?
RNA polymerase
What does RNA polymerase do?
it catalyzes the reaction, which pulls the DNA strands apart and starts putting together RNA nucleotides
What does the ending, “ase,” mean?
an enzyme
What is the promoter region?
the DNA sequence where RNA polymerase binds
What is a terminator?
the sequence signalling the end of transcription
How many codons are there? And what is their breakdown?
There are 64 codons. 61 of them code for amino acids, and 3 are terminators
What do tRNAs carry on their ends?
each tRNA carries a specific amino acid on one end and an anticodon on the other end.
What does the anticodon pair with?
The anticodon base pairs with the complementary codon on the mRNA
How long is a tRNA molecule?
about 80 nucleotides long
What is a tRNA molecule made out of?
made of a single RNA strand
What is the rough shape of tRNA, why is it shaped like this?
It is roughly L shaped due to the hydrogen bonds (it twists and folds)
What helps bring the tRNA anticodon with the mRNA codon in protein synthesis?
ribosomes.
What are the 3 binding sites for tRNA and where are they?
A, P, E in the ribosome
What is in the A site?
it holds the tRNA that carries the amino acids to be added to the chain
What is in the P site?
it carries the growing polypeptide chain
What is in the E site?
it is the exit site, where the tRNA that’s now empty leaves the ribosome
What is a mutation?
changes in the genetic material of a cell.
What are the three types of mutations?
Point, missense and nonsense
What are point mutations?
they are chemical changes in just one base pair of a gene
What are the two types of point mutations?
base pair substitutions or base pair insertions or deletions
What is a base pair substitution?
It replaces one nucleotide and its partner with another pair of nucleotides
What is a silent mutation?
a mutations that has no effect on the amino acid produced by a codon because of redundancy of the genetic code
What is a missense mutation?
It is a change in the amino acid. It will still code for an amino acid, but not the same amino acid
What is a nonsense mutation?
It is the most severe type, it is a replacement of a single nucleotide.
What can sometimes happen in a nonsense mutation?
It can change an amino acid codon into a stop codon, nearly always making a non-functional protein.
Insetions and Deletions
additions and losses of nucleotide pairs in a gene
a frameshift mutation
the insertion or deletion of nucleotide bases in numbers that are not multiples of three
