Biology Checkpoint Questions Chapter 9

Front 1

How does DNA replication occur?

Back 1

Two strands of the DNA double helix separate, and a new complementary strands are synthesized by DNA polymerase in the 5' to 3' direction, using the original strands as templates. Enzypes called topoisomerases prevent DNA from tangling during replication, and two strands, separate at the replication fork by enzymes knwn as helicases, are starbilized at the replication fork b yenzymes known as helcases, are stablized by single-strand binding proties

Front 2

What is the nature of the genetic code, and in what sense is it universal?

Back 2

1. Nucleotides constitute a ____ for the amino acids. Nucleotides stored in the double helix of DNA, that specifies the quite dissimilar structures of protein molecules. There are four molecules, (short terms) A,T,C,G.
2. "One of the most remarkable discoveries of molecular biology is that the ____ is nearly identical in all organisms, with only minor exceptions..."

Front 3

What are the four molecules of DNA?

Back 3

A - Adenine
T - Thymine
C - Cytosine
G - Guanine

Front 4

What are the four molecules of RNA?

Back 4

A - Adenine
U - Uracil
C - Cytosine
G - Guanine

Front 5

What are the main steps in the transcription of RNA from DNA?

Back 5

-follows similar replication rules
-Catalyzed by enzyme RNA polymerase.
- Carry the genetic message from the DNA to the ribosomes, which are composed of ribosomal RNA and proteins.

Front 6

Where does translation occur in a eukaryotic cell, and what are the major steps that occur in the process?

Back 6

The ribosomes, which occur in the cytosol, are the actual sites of protein synthesis. The role of transfer RNA molecules, each of which is specific for a particular amino acid, is to translate the coded nucleotide sequence of mRNA into the amino acid sequence of protein. Then the tRNA molecules cary the amion acids to the ribosomes where they attach toa growing polypeptide. This ribsomoe-mediated synthesis, this called ____.

Front 7

What are some factors of regulating gene expression in eukaryotes?

Back 7

At some stage these cells begin to differentiate, becoming different cells types (epidermal, photsynthetic, etc.)

Front 8

How are (1) "complementary bases" and (2)"antiparallel strands" involved in the structure of DNA?

Back 8

1. Each strand contains a sequence of bases that will pair in a specific way with the bases in the other strand, and thus the sequences of bases in each strand can be used to determine the sequence of bases in the ____.
2. The two strands run in opposite directions, that is, the direction from the 5' end to the 3' end of one strand is opposite that of the other strands, called ____.

Front 9

Show here is the sequence of bases in 5' and 3' direction in one strand of hypothetical DNA molecule. Identify the sequences of bases in teh complementary strand.
5'-AAGTTTGGTTACTTG-3'

Back 9

3'----------5'
3'-TTCAAACCAATGAAC-5'
What is the completmentary strand? 5'-3'

Front 10

What would the sequence of an mRNA molecule transcribed from the DNA molecule?
5'-AAGTTTGGTTACTTG-3'

Back 10

5'-TTCAAACCAATUTTC-3'

Front 11

Orgin of replication

Back 11

Initiation of DNA replication always begins at a specific nucleotide sequence known as ___.

Front 12

Replication bubble

Back 12

If DNA caugt in the act of replication is viewed under the electron microscope, the localized regions of synthesis appear as "eyes" or ______.

Front 13

Replication fork

Back 13

At either end of a ___, where the existing strands are being separated and thenew, complementary strands are being synthesized, the molecule appears to form a Y-shaped structure, known as a _____.

Front 14

Replication/transcription/translation

Back 14

-Occurs in DNA, the molecule "unzips locally" with the paired bases separating as the hydrogen bonds are broken. Two strands seperate and give templates; for the formation of a new strand. THE SYNTHESIS OF DNA.
-Synthesis of mRNA, which is a copy of a portion of one strand of the double-stranded DNA helix.
- Synthesis of a polypeptide directed in teh nucleotide sequence of the mRNA.

Front 15

mRNA/tRNA/rRNA

Back 15

messanger RNA (transcription)
transfer RNA (translate)
ribosomal RNA (mRNA is to carry the genetic message from the DNA to the ribosomes, which are composed of ____ and proteins.

Front 16

A site/P site/E site

Back 16

Aminoacyl, where the incoming amino acid-bearing tRNA usually binds.
Peptidyle, where the tRNA bearing the growing polypeptide chain resides.
Exit, from which the tRNAs leave teh ribosome after they have released their amino acids.

Front 17

Codons/Anticodons
Euchromatin/Heterochromatin
Introns/Exons

Back 17

Sequence of three adjacent nucleotides in a molecule of DNA or mRNA that form the code for a single amino acid, or for the termination of a polypeptide chain.
In a tRNA molecule, teh three-culeotide sequence that base-pairs with the mRNA codon for the amion acid carried by the particul tRNA; the ___ is complementary to the mRNA codon.
The more open chromatin, which stains weakly.
The more condensed chromatin, which stains strong.
Noncoding interruptions within a gene are known as intervening sequences, or ____.
The coding sequences - the sequences that are translated into protein - are called ____.

Front 18

Why is genetic code said to be degenerate?

Back 18

With 61 combinations coding only 20 amino acids, you can see that there must be more than one codon for many of the amino acids; hence, the genetic code is said to be ___.