Molecular Genetics Flashcards
What are the building blocks of DNA?
Adenine (A), thymine (T), cytosine (C), and guanine (G).
Describe the structure of DNA (shape, molecules that connect, etc.).
It is a double helix (2 strands of nucleotides), it is a spiral-shape. Phosphate backbone connects to sugar (deoxyribose), which connects to a nucleotide.
What are the base pairs that form DNA?
T-A (thymine pairs with adenine), G-C (guanine pairs with cytosine), A-T, C-G.
What type of bond connects the base pairs?
A hydrogen bond.
Hydrogen bonds are (weaker/stronger) than covalent bonds.
Weaker.
Why is it good that hydrogen bonds, used to connect base pairs, are weak?
Because they need to break so that the DNA can separate for replication.
During which stage of the cell cycle does DNA replication occur?
Interphase.
Each parent DNA molecule has how many complementary strands?
Two.
What is the first step in replication?
Separating the two DNA strands.
How do the parent strands help with building new DNA?
They are a template for determining the order of the nucleotides along the new complementary strand.
How are nucleotides added to the single strand?
A special enzyme attaches floating nucleotides to the complementary strand.
The nucleotides connect to form…
The sugar and phosphate backbone for the new strand.
Each daughter (new) DNA molecule is made of…
One parent strand and one new strand.
How many nucleotides are added to the strand each second?
50.
How many base pairs are there in 46 DNA molecules (chromosomes) ?
6 billion.
How long does it take to replicate the 6 billion base pairs in 46 DNA molecules?
A few hours.
Are many mistakes made during DNA replication? Why/why not?
Few mistakes are made due to repair enzymes.
If you laid the DNA in a single human cell end-to-end, how long would it be?
Six feet.
What is DNA polymerase?
An enzyme that binds the new nucleotides together.
What is helicase?
The enzyme that unwinds the DNA.
Genetic traits are the result of…
Proteins.
DNA has instructions for making…
Proteins.
What is alkaptonuria?
It is a rare inherited genetic disorder of amino acid metabolism, meaning that the person cannot digest/metabolize amino acids/proteins. They are essentially allergic to protein because if they eat it, it must be medically removed.
What are proteins made of?
A specific number of amino acids in a specific sequence.
What has the instructions for making the proteins?
DNA.
Why are proteins important in our body?
They build our structure (muscle and bones), hormones, and they are enzymes.
What is central dogma?
An explanation of the flow of genetic information within a biological system. It says that DNA turns into RNA through transcription, and RNA becomes protein through translation.
How is RNA different from DNA?
RNA is a single strand, it uses ribose sugar instead of deoxyribose, and it has uracil to pair with adenine instead of thymine.
What is transcription?
When one side of the DNA is copied to make RNA.
What are the three types of RNA?
mRNA, tRNA, and rRNA.
When copying DNA, one side goes in the…to… direction while the other goes in the…to… direction.
3’ to 5’, and 5’ to 3’.
How many bases are exposed at a time by the replication bubble?
10 bases.
What does mRNA stand for?
Message RNA. (This is the basic RNA.)
What does tRNA stand for?
Transfer RNA.
What does rRNA stand for?
Ribosomal RNA.
What does rRNA do?
It combines with proteins to make ribosomes.
What is translation?
Turning RNA into proteins. (Translating the sequence of nucleotides on the mRNA strand to a sequence of amino acids during protein synthesis.)
What is a codon?
Three letters on the mRNA.
Define stop and start codons.
These determine where on the strand translation begins and where it ends.
How many different amino acids are necessary for humans?
20.
How many different codons are there?
64.
How many different stop codons are there?
3.
What are the three stop codons?
UAG, UAA, UGA
What is the most common start codon?
AUG. (This codon determines where to start making the protein.)
What does tRNA do?
It transfers/ carries amino acids to the ribosome.
What is translation?
Translating the RNA message into a polypeptide (amino acid chain), requiring ribosomal units, mRNA, tRNA, amino acids, and ATP.
What happens during translation initiation?
The mRNA binds to ribosome and initial tRNA. It requires a start codon, which attaches to the tRNA. The ribosome also attaches to the tRNA.
What is an anticodon?
The three exposed letters that are the opposite letters of the codon. Ex: Codon: UGG, anticodon: ACC.
What is elongation?
Adding amino acids to the ribosome, three codons at a time. This continues until it hits a stop codon.
What is translation termination?
When the ribosome comes to a stop codon and accepts the release factor. The polypeptide is freed.
Define gene.
The area of DNA where you make a protein from, where the final product is either a polypeptide or an RNA molecule. The mRNA will be degraded by enzymes.
Where does DNA replication start and where does the protein synthesis end?
The whole process starts inside the nucleus and then ends up in a ribosome outside the nucleus.
What does RNA polymerase do?
It makes RNA.
What is the replication bubble?
The portion of the DNA that is unzipped for replication.
After RNA is made, what happens?
The RNA copy leaves the nucleus. Ribosome attaches to it and turns the RNA information into a string of amino acids that becomes a protein.
After the amino acids are made, what happens?
The transfer molecules bring the amino acids to a “factory.” The amino acids attach to the correct letter (base pair).
What does mRNA do?
It is an intermediate message that is translated to form a protein.
What does tRNA do?
It brings amino acids from the cytoplasm to a ribosome to help make the growing protein.
What does rRNA do?
It forms part of ribosomes, a cell’s protein factories.
