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15 Cards in this Set

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3. Describe the four evidences that led Watson & Crick to the structure of DNA
1)DNA is a polmer of nucleotides each one having a phosphate group, the Sugar deoxyribose and a nitrogen containing base

2)Chargaff discovered that Purines always equal the number of Pyrimidines, Also Adenine equals the amount of thymine and Guanine equals the amount of Cytosine

3)Franklin and Wilkins used an X-ray diffraction photograph of DNA showing the DOUBLE HELIX

4)A and T are held together by 2 hydrogen bonds
and G and C are held together with 3 hydrogen bonds
1. What was the purpose of the experiment in figure 24.1?
To find out if Protien or DNA is responsible for Heredity
What was the conclusion of the viral experimant, and why?
DNA is the material of heredity because when it was filled with radiation and Protien was filled with radiation it was the DNA that found itself inside bacteria in an X-ray that exposed the radiation on the DNA
2. What are the three parts of a nucleotide?
Deoxyribose sugar
Nitrogen base
Which parts make up the DNA “backbone,
Deoxyribose sugar
---these alternate making up the backbone
which make up the “steps” Of a DNA double Helix
Nitrogen containing base pairs Adening with Thymine
Guanine with Cytosine
Describe the process of DNA replication, particularly what is meant by "old" and new" strands.
The enzyme DNA helicase unwinds and unzips the double stranded DNA(the weak H bonds break)

2)DNA nucleotides fit into place by complementary base pairing they are joined by the enzyme DNA polymerase

3)DNA ligase seals any breaks in the sugar phosphate backbone

4)The old strand is identicle to the new strand (semiconservative replication because the new strand is composed of an old parental strand)
5. What role do hydrogen bonds play in DNA structure and function?
1) H bonds are the deciding factor that allows A and T toe be attracted and G and C

2) H bonds Hold the A and T and G and C together forming the rungs of the double helix
Gene expression
With the help of RNA a gene(a segmant of DNA) specifies the sequence of amino acids in a polypeptide, in this way genes control the structure and metabolism of cells
The enzyme RNA polymerase copies a strand of the DNA into an RNA molecule. It then matures removing all the introns and leaves the nucleus of the cell
Describe RNA
Deoxyribose is the sugar
it uses Uracil as a base instead of Thymine
It is single stranded
It is not a Helix
During translation the sequence of bases in mRNA determines the order that tRNA amino acids come to a ribosome and therefore the order of amino acids
Each three letter nucleotide unit of an mRNA molecule
anti codon
the 3 letter sequence on a tRNA that is holding an amino acid
8. How can a bacterium be made to produce a human protein? (fig 24.15).
You take a gene out of a human cell

You Use a restriction enzyme to cleave the DNA of a Plasmid in a bacterium

You insert the Human DNA in the Plasmid and seal it with ligase

The bacteria host cell takes up the new recombined Plasmid and now the plasmid reproduces along with the cell.