Final Exam Chapters 2-8

Question 1

How does the structure of DNA facilitate its replication?

Answer 1

The two strands of DNA are antiparallel. The DNA double helix make the two strands of DNA complementary, so each strand can act as a template for building a new strand.

Question 2

How do leading strands replicate?

Answer 2

The leading strand has its 3’ end pointing toward the replication fork so its synthesized in one long continous polymer as the parental strand unwinds.

Question 3

How do the lagging strands replicate?

Answer 3

The 3’ end points away from the replication fork so its synthesized in short discontinous pieces called okazaki fragemtents.

Question 4

Describe the central dogma.

Answer 4

DNA 
Transcription
 RNA 
Translation
Polypeptide.

Question 5

What are the roles of DNA, RNA and ribosomes in transcription?

Answer 5

RNA polymerase synthesizes the RNA transcript in the 5’ to 3’ direction. As the DNA unwinds the growing RNA strand forms a duplex with the DNA template. The primary transcript combines with ribosome to direct protein synthesis is called mRNA.

Question 6

What is the role of ribosomes in translation?

Answer 6

Translation takes place on ribosomes. Ribosome ensures that the sequence in the mRNA coding for amino acid is read in continous, nonoverlapping groups of 3 nucleotides. Ribosome has a large subunit that contains 3 binding sites for tRNA.

Question 7

What are the roles of RNA and in tranlation?

Answer 7

tRNA (transfer RNA) picks uo the appropriate amino acid at its 3’ end and uses an anti codon to recognize the appropriate codons the the mRNA.

Question 8

What is the genetic code? What are the start and stop codons?

Answer 8

Most codons specify an amino acid. 20 amino acids are specified by 64 codons. But each codon only codes for one amino acid. AUG is the start codon and UAA UAG UGA are the stop codons.

Question 9

How do u solve a generic code question?

Answer 9

1. Find out the template DNA. It is read 3’ to 5’.
2. Since the mRNA is complementary to the template, write the bases in the 5’ to 3’.
3. Since the tRNA is complementary to the mRNA write the bases in the 3’ to 5’ direction.
4. Use the genetic code to write the amino acid. Make sufe younuse the mRNA codons to find the amino acid.

Question 10

What is mutation?

Answer 10

A spontaneous change in the sequence of the generic material.

Question 11

What is synonymous and nonsynonymous mutation?

Answer 11

Synonymous mutation is a nucleotide substitution that does not change the amino acid.
Nonsynonymous mutation is a nucleotide substitution that changes the amino acid.

Question 12

What is a nonsense mutation?

Answer 12

When a point mutation changes an amino acid to a stoo codon that terminates translation early resulting in incomplete polypeptide.

Question 13

What is frameshift mutation?

Answer 13

Insertion or deletion of 1 or 2 bases results in shifting of the reading frame.

Question 14

What are the common features found in all cells?

Answer 14

1. Plasma membrane.
2. Cytoplasm.
3. Ribosomes.
4. Chromosomes.
5. Cytoskeleton.

Question 15

What are the differences between plant and animal cells?

Answer 15

Plant cells have cell wall, central vacuole and chloroplast while animal cells have lysosomes and centrosomes.

Question 16

What is the endomembrame system and what are the organelles present?

Answer 16

Many organelles communicate with other organelles within a cell either through direct physical contact or by the transfer of membranous vesicles. The endomembrane system consists of the nucleus, endoplasmic reticulum, golgi apparatus, lysosomes and ribosomes.

Question 17

Describe the relationship between protein folding and function.

Answer 17

The tertiary structure determines the protein function by the contours and distribution if charge outside the molecule and the presence of cavaties that might bind with smaller molecules on the inside.

Question 18

Distinguish between catabolism and anabolism.

Answer 18

Catabolism is the breakdown of molecules into smaller units, producing ATP.
Anabolism is the building of molecules from smaller units, requiring ATP.

Question 19

Distinguish between endergonic and exergonic reactions.

Answer 19

Reactions with a negative delta G release energy and are exergonic (catabolic reaction).
Reactions with a posistive delta G require energy and are endergonic (anabolic reactions).

Question 20

How do enzymes catalyze chemical reactions?

Answer 20

The interaction between the substrate and active site of the Enzymes is able to reduce activation energy by stabilizing the transition state.

Question 21

How does feedback regulate chemical reactions?

Answer 21

If the cell is producing more product than it needs, the product acts as an inhibitor - called negative feedback. This is beneficial because the cell can self regulate.

Question 22

What is an allosteric enzyme?

Answer 22

An enzyme that is inhibited or activated when binding to another molecule by causing its shape to change.

Question 23

Describe the structure of the mitochondria.

Answer 23

The mitochondria has an Inner and an Outer membrane. The space between these two membranes is called the intermembrane space. The space inside the inner membrane is the mitochondrial matrix.

Question 24

How is the energy in a glucose molecule released during cellular respiration?

Answer 24

Most of the energy in glucose is transferred to electron carriers. The energy in NADH and FADH2 is released in a series of redox reactions thaf occurs as electrons pass through the ETC. This pumps H+ across the inner mitochondrial membrane creating an electrochemical proton concentration gradient which provides a source of potential energy that is used to drive the regeneration of ATP.

Question 25

Differentiate between fermentation and aerobic respiration.

Answer 25

Fermentation uses substrate level ohosphorylation instead of oxidative phosphoylation to regenerate ATP. Fermentation couples with glycolysis plus a reaction that regenerates NAD+.

Question 26

Why is aerobic respiration and fermentation considered catabolic reactions?

Answer 26

Both start with a glucose and end with smaller units due to the breakdown of glucose through glycolysis and produce ATP.

Question 27

What are the components of chloroplasts?

Answer 27

Chloroplasts are enclosed by a double membrane. Inside has a highly folded membrane known as the thylakoid membrane. The photosynthetic ETC is located in the thylakoid membrane.