Describe the structure of DNA.
Double Helix
What are the 3 components of a DNA nucleotide?
1. Nitrogenous base
2. Deoxyribose Sugar
3. Phosphate group
What are the 4 bases found in DNA?
1. Adenine
2. Thymine
3. Cytosine
4. Guanine
What are the base pairing rules?
A-T / C-G
When and where in the cell does DNA replication occur?
In the cell's NUCLEUS during the S PHASE
What happens during DNA replication
the enzyme HELICASE UNZIPS the DNA molecule between the bases, while the enzyme DNA POLYMERASE adds new NUCLEOTIDES to the original strand.
What is the outcome of DNA replication?
TWO genetically IDENTICAL STRANDS of DNA
Why must the cells chromosomes (DNA) be replicated prior to cell division (mitosis & meiosis)?
So each cell recieves a copy of the original cell's genetic instructions (In mitosis, each cell recieves full amount; in meiosis, each cell recieves 1/2 of the originals cell's DNA)
What is the first step in protein synthesis?
TRANSCRIPTION of an active gene forming a mRNA molecule.
What is the name of the enzyme that makes mRNA molecule from the specific sequence of bases in the gene ?
RNA Polymerase
after the first step in protein synthesis (transcription), the mRNA molecule is then processed, in which ________ are removed and __________ are bonded back together.
Finally, a guanine __________ and poly-A __________ are added to the mRNA.
introns, extrons, cap, tail
In protein synthesis
The final mRNA leaves the ______________ and goes into the cytoplasm and attaches to a ______________.
nucleus, ribosome
according to the instructions in the mRNA base sequence the ribosome puts together a chain of _______ ________ in the order that the _______ brought them to the ribosome.
amino acids, tRNA
Finally, the amino acid chain is ___________/ ___________ to form a functional protein.
folded/modified
A DNA gene sequence is CCA. Name the mRNA codon sequence
GGU
Name the tRNA anticodon sequence
CCA
Name the amino acid sequence
gly
What are the three types of RNA and the functions of each?
mRNA- brings gene message to ribosome
tRNA- brings amino acids to ribosome
rRNA- is found in ribosomes, which attach amino acids together in the order that tRNA brings them to the ribosome.
(THERE ARE 20 DIFF. AMINO ACIDS USED TO MAKE PROTEINS)
What is a gene mutation?
A permanent change in DNA base sequence
What are some common mutagens?
1. UV Radiation
2. some viruses
3. carcinogens (cigarette smoke)
4. mistakes by DNA Polymerase during DNA replication
5. ionizing radiation (gamma rays, x-rays)
which of the following gene mutations would have the greatest NEGATIVE impact on the protein produced:
-deletion of a single base near the end of the gene
-deletion of a codon near the beginning of the gene
-substitution of a single base in the middle of
insertion of a base near the beginning of a gene
Are gene mutations usually good or bad?
Gene mutations are usually BAD for cells
Does a gene mutation always affect the protein produced?
NO, some mutations change the codon sequence but not the amino acid sequence.
Your skin cells and nerve cells contain the same exact sequences of DNA. However, they differ in both structures and function, why?
The genes in your skin and nerve cells are the same, but each cell uses a different combination of genes . Humans have 21,000 genes, but not all genes are used in all cells