A quick review! AKA: What you SHOULD know by now. . The structure of chromosomes: A chromosome consist of DNA tightly coiled around proteins. What is a gene? A segment of DNA that codes for a protein or RNA molecule. DNA is copied during the S phase of the cell cycle.
The structure of chromosomes: A chromosome consist of DNA tightly coiled around proteins.
What is a gene? A segment of DNA that codes for a protein or RNA molecule.
DNA is copied during the S phase of the cell cycle.
Changes in DNA are called Mutations.
Original DNA strand: ABCDEFG
Types of mutations:
1)Deletion:ABCEFG – a nucleotide is missing
2) Substitution: ABKEFG – a nucleotide is substituted (K for C).
3) Insertion: ABGCDEFG – a nucleotide is inserted (G). All other nucleotides are present.
4) Translocation: ABCDJEFG – a nucleotide is brought in that is not in the original strand at all.
5) Replication: ABBCDEFG – a nucleotide is repeated.
And, last but not least- don’t forget Mendel’s Theory of Heredity:
For each inherited character, an individual has 2 copies of the gene- one from each parent.
There are alternative versions of genes.
When two different alleles occur together, one of them may be completely expressed, while the other may have no observable effect on the organism’s appearance.
When gametes are formed, the alleles for each gene in an individual separate independently of one another.
Section 1 Key Terms:
Vaccine: a substance that is prepared from killed or weakened disease-causing agents, including certain bacteria.
Virulent: Describes an organism that is able to cause disease.
Transformation: A change in genotype caused when cells take up foreign genetic material.
Bacteriophage: AKA ‘phage’; it is a virus that infects bacteria.
QUIZ TOMORROW ON THESE TERMS.
Frederick Griffith was researching a vaccine for pneumonia and discovered that genes could be changed when cells take up foreign material. This change in genetic material is called transformation.
This is what he knew, but he didn’t know why it happened.
Viral Genes & DNA
Take out one sheet of paper. Match the terms with the correct definition.
1) This describes a microorganism or virus that causes disease and that is highly infectious.
2) A virus that infects a bacteria.
A substance prepared from killed or weakened pathogens and introduced into a body to produce immunity.
The transfer of genetic material in the form of DNA fragments from one cell to another or from one organism to another.
Answer the following questions using the choices below. Write the correct letter.
Who discovered transformation?
Who performed the first experiment that correctly identified the molecule that carries genetic info as DNA and not proteins?
1. Double Helix
4. Base-Pairing Rules
5. Complementary Base Pair
Quiz tomorrow on these terms.
Purines are nucleotides that are bulky and double-ringed.
Pyrimidines are nucleotides that are small and single-ringed.
The nitrogen base in a nucleotide can be Thymine, Cytosine, Adenine, or Guanine.
Chargaff: 1948, Erwin Chargaff discovered that for each organism he studies, the amount of adenine always equaled the amount of thymine and that the amount of guanine always equaled the amount of cytosine. Now, we know why.
Wilkins and Franklin: Developed high X-ray diffraction photographs of strands of DNA. These photos suggested that DNA resembled a tightly coiled helix and was composed of three chains of nucleotides.
Watson and Crick: They took this info and their knowledge of chemical bonding and determined the structure of DNA.
Study Section 2 terms and end of section questions (pg 197 #1,4,5,6). Be ready for a Bellwork Quiz on vocabulary.
Take out one sheet of paper. Number your paper 1-5. Match the terms (the correct letter) with the correct definition.
1. Double helix 4. Base-Pairing Rules
2. Nucleotide 5. Complementary Base Pairing
a. The rules stating that cytosine pairs with guanine and adenine pairs with thymine in DNA, and that adenine pairs with Uracil in RNA.
b. In a nucleic-acid chain, a subunit that consists of a sugar, a phosphate, and a nitrogenous base.
c. A characteristic of nucleic acids in which the sequence of bases on one strand is paired to the sequence of bases on the other.
d. The spiral staircase structure characteristic of the DNA molecule.
e. A five-carbon sugar that is a component of DNA nucleotides.
DNA Replication: the process of making a
copy of DNA.
Steps of DNA Replication:
An enzyme called DNA helicasebreaks
the hydrogen bonds that link the two DNA
strands together. The double helix unwinds
and the two original DNA strands separate. Once the two strands are separated, additional proteins attach to each strand in order to hold them apart and keep them from wrapping back together. The areas where the strands are held apart are called replication forks.
2) At the replication fork, DNA polymerases add complementary nucleotides to each strand, according to the base pairing rules.
3) Two DNA molecules form that are identical to the original DNA molecule.
DNA helicasesseparate the two original DNA strands.
DNA polymerases add complementary nucleotides to each strand.
Two DNA molecules form that are identical to the original DNA molecule.
This process occurs atmultiple placesthroughout the strand of DNA, until replication is complete.