Test 2 Semester 2 Flashcards
What roles do telomeres play in DNA replication?
telomeres prevent replication from skipping the ends of the DNA sequence
What differences are there between DNA &and RNA
RNA has ribo nucleic acid, and ribose sugar unlike DNA,
and instead of thymine it has Uracil
What are the 4 functions of DNA polymerase?
1-To code DNA
2-to catalyze cell’s reactions in the cell
3- to check for mistakes when coding
4-helping to transfer DNA to RNA
What are the three bases of tRNA called that are complimentary to 3 bases on mRNA?
Thynine – Adenine
Guanine – Cytosine
Adenine – Uracil
What is transcription?
When a strand of DNA is used as a template to make a complimentary strand of RNA
What is Translation?
Translation is when the ribosome uses mRNA to make codons into amino acids which will form a polypeptide chain.
What causes translation to stop?
stop codons
Give at least one example of a stop codon:
UGA
UAA
UAG
What are mutations?
Heritable changes in genetic information
What does a cell use to decode DNA?
RNA
What does RNA do?
Protein synthesis
What is the first step in making proteins from DNA?
A cell must copy part of a DNA molecule into RNA
What is the second step in making proteins from DNA?
RNA uses the instructions to produce proteins
What are the three main types of RNA?
Messenger RNA (mRNA):carries info from DNA to other parts of the cell Ribosomal RNA (rRNA): make up ribosomes, where proteins are made Transfer RNA (tRNA): transfer the amino acids to the ribosome when they are building proteins
How does the cell make RNA?
Transcription
Where is RNA made in prokaryotes and eukaryotes?
Prokaryotes: cytoplasm
Eukaryotes: Nucleus
What happens to RNA before it is sent out into the cell to make proteins?
Called pre-mRNA
RNA is edited and the pieces known as introns are removed, and the remaining pieces called exons are spliced together
What makes up proteins?
Long chains of amino acids called polypeptide chains that determines the properties of different proteins
How many different 3 base codons are possible?
64
How are genetic messages decoded?
base sequence is transcribed from DNA to RNA
the transcribed info contains the code for making proteins
What is an example of a start codon?
AUG
Where does the ribosome come into play and what does it do?
Ribosomes use the sequence of codons in mRNA to assemble amino acids into polypeptide chains
(this is known as translation)
once complete the chains fold into their appropriate protein shape
Steps of Translation:
- DNA is transcribed into mRNA in the nucleus
- mRNA is then sent to the cytoplasm
- ribosome attaches to mRNA
- Codons pass through the ribosomes (they are being read)
- tRNA brings the appropriate amino acid for every codon
- Ribosome attaches the amino acids to the growing polypeptide chain using a peptide bond
- the polypeptide chain grows until a stop codon is reached
- the polypeptide chain and mRNA are then released by the ribosome
How does tRNA know which amino acid to attach?
each tRNA molecule carries just one kind of amino acid
How do the three types of RNA come together during translation?
mRNA: carried coded message
tRNA:delivers amino acids that are called for by the codons and enables ribosome to read the mRNA
rRNA: hold ribosomal proteins in place, locates the start codon, and bonds amino acids together
How do proteins affect the traits/genes in organisms?
- Many proteins are enzymes that catalyze/regulate reactions
- Enzymes can control pigments in organisms
- proteins can regulate growth
All living things produce proteins in this way?
3 bases at a time
Does a single strand from the double helix contain all of the information needed to reconstruct the other half of the strand?
Yes, it is the mechanism of base pairing.
The strands are complimentary, each strand can be used to make the other strand.
What is replication and what part of the cell cycle does this occur in?
Duplication of DNA & S phase = synthesis
Prokaryotic DNA replication?
Regulatory proteins bind to a single starting point, replication proceeds in both directions until the entire chromosome is copied.
Eukaryotic DNA replication?
Replication begins at many different places along the length of a chromosome. Replication proceeds in both directions until a complete set of chromosomes is produced
What if DNA ploymerase misses a mistake?
Damaged regions are replicated and It may alter certain genes.
Can have serious consequences such as Cancer and Huntington’s disease
Polyploidy
Extra sets of chromosomes
larger and stronger
typically occurs in Fruits & Fish
How do mutations occur?
Cell inserts the wrong base or even skips a base as DNA is made.
This can result in 2 types of mutations:
Gene mutations- Mutations in a single gene
Chromosomal mutations- changes in a whole chromosome
What is a point mutation?
Changes in one or few nucleotides occurs at a single point in replication there are three types of point mutations: Substitution Insertions & Deletions
Substitution?
1 base is changed
affects 1 amino acid
almost no overall affect
Insertions?
one base is inserted
insertions and deletions are known as frameshift mutations
Deletions?
1 base is removed (insertions and deletions are known as frameshift mutations)
Frameshift mutations?
Can have a dramatic affect. Causes the entire sequence of codons to be shifted. Can change every amino acid that follows the point of mutation, and can also alter mutations to the point that it will not function.
Chromosomal mutations?
Can change the location of genes on a chromosome Four types: 1.Deletion 2.Duplication 3.Inversion 4.Translocation
Deletion?
loss of all or part of chromosome
Duplication?
Produces an extra copy of all or part of chromosome
Inversion?
Reverses the direction of parts of the chromosome
Translocation?
When a part of a chromosome breaks off and attaches to a different chromosome
How do mutations affect genes?
Some have little to no affect.
Some are beneficial.
Some are harmful.
What are Mutagens?
Chemical or physical agents in the environment
Pesticides, smoke, pollutants
Radiation, (x-rays,UV)
Harmful Mutations
Those that change protein and cell activity
genetic disorders
cancer
sickle cell
Helpful Affects
Can produce proteins with new or altered functions
Can be helpful in different/changing environments
resisting pesticides/herbicides
resisting bone fractures and HIV
