Chapter Four

Question 1

What is the purpose of nucleic acids?

Answer 1

Storage and transmission of genetic information

within the code of DNA gives us the code for RNA/proteins - transcription is DNA to RNA - (gene expression)

Question 2

what are the monomers of nucleic acids?

Answer 2

nucleotides

Question 3

Explain the differences of nucleotides vs nucleosides

Answer 3

Nucleotides are made of three things, a pentose sugar, a nitrogenous base and a phosphate group

Nucleosides are made of two things, a pentose sugar and a nitrogenous base

Question 4

What does transmission and storage mean in relation to nucleic acids?

Answer 4

The storage of genetic information means that within our code of DNA contains the instruction for transcribing into RNA then translating proteins.

Question 5

How are DNA and RNA different (four ways)

Answer 5

DNA and RNA have different pentose sugars (deoxyribose ribose)
DNA is double stranded and RNA is single stranded
They have slightly different nucleosides (#2)
They have different pyrimidine bases DNA = C-T’s RNA = C-U’s

Question 6

How do you know what carbon is which one in a sugar?

Answer 6

you start from the oxygen and count to the right

Question 7

What are the two types of nitrogenous bases? Briefly explain their structure and explain which ones are which.

Answer 7

Two types are purines and pyrimidines

Purines are a double fused ring structure of six carbon and are Adenine and Guanine

Pyrimidines are a single ring six carbon structure and are Cytosine, Thymine and Uracil

Question 8

Draw out the three basic parts of a nucleotide.

Answer 8

phosphate group attached to a penta-sugar attached to a nitrogenous base

Question 9

How are nucleotides joined together and broken apart?

Answer 9

Condensation reaction/ hydrolysis reaction

Question 10

What is a phosphodiester linkage?

Answer 10

the bond created when a condensation reaction happens between two nucleotides on their 5 prime and 3 prime carbons.

the phosphate group links the 5’ and 3’ carbons

Question 11

Why does DNA/ RNA grow only in the 5’ to 3’ direction?

Answer 11

Because of the shape of the enzymes / proteins can only perform their actions in one specific direction, and generally because of its antiparallel nature

Never add a nucleotide to a five prime end, only the three prime end

Five prime end has the phosphate group and the three prime has the hydroxyl at the end of the connection

Question 12

How do two strands of DNA stay together?

Answer 12

through the process of complimentary base pairing —- when purine base ends bond with pyrimidine base ends through hydrogen bonds to hold them together

How many hydrogen bonds between A-T? 2
How many hydrogen bonds between C-G? 3

Question 13

Is base pairing only possible in DNA?

Answer 13

No it can also happen in RNA as it can occur between different regions and as expected it changes in 3‐D structure

Question 14

What is the basic structure of DNA that we can see across the board in all species?

Answer 14

A double helix that has a sugar-phosphate backbone and nitrogenous base rungs

the genetic info info is carried in the base rungs

Question 15

Why is base pairing between RNA/DNA so important?

Answer 15

because the complimentary base pairing can change the structure of the DNA or RNA and when something has its structure changed its function also changes.

base pairing between RNA and DNA is also possible, and becomes very important in transcription of DNA to RNA

Question 16

Describe how an RNA nucleic acid is paired.

Answer 16

single strand but can fold on itself in specific regions

Question 17

Why is DNA so important? (two reasons)

Answer 17

it encodes hereditary information from generation to generation and also duplicates itself by process of replication

It transcripts into RNA and translates in protein formation

Question 18

Name three other nucleotides.

Answer 18

ATP - energy transfer

GTP - energy transfer in protein synthesis

cAMP - essential to action of hormones and transmission of
info in the nervous system

Question 19

Describe the antiparallel nature of the DNA double helix.

Answer 19

the outer sugar phosphate “strands’ of DNA run anti parallel which means they run in opposite directions one has the 5’ Carbon at the top and the other has it at the bottom

Question 20

Is all of our DNA transcripted? What about replicated?

Answer 20

It is all replicated but not all translated, about 90% is.

Question 21

Difference between translation and transcription.

Answer 21

Transcription is a process that turns DNA into RNA

Translation is a process of RNA to Protein.

Question 22

What two famous experiments that didn’t support the concept of spontaneous generation.

Answer 22

Redi’s meat jars (three jars, one with cheese cloth, nothing, and lid

Louis Pasteur (put nutrient medium in sterile flask and then broke one of the necks off the flask and microorganisms only showed up in one)

Question 23

How old are the oldest proto cells we have found as fossils?

Answer 23

3.5 billion years old.

Question 24

What are the two theories for how life first appeared on earth?

Answer 24

Chemical Evolution - conditions were conducive to form simple molecules amino acids, purines pyrimidines led to formation of simple life forms

Life outside earth - simple life forms came from a meteorite and they actually found amino acids nucleotide bases, and sugars

Question 25

What came first nucleic acids, proteins or something else?

Answer 25

It is likely that catalytic RNA was the first (not actually RNA of what we know it as), because these parts of the macromolecules couldn’t just go together, they had to have something to speed up their reaction.

It is said that RNA could have acted as a catalyst for its own replication and synthesis of proteins

Evidence to back this up is that the 3D shape of certain RNA molecules look similar to enzymes

Question 26

What are riboenzymes?

Answer 26

catalytic RNA’s that speed up reactions involving their own nucleotides

Question 27

Evidence for an RNA world (5 things)

Answer 27

1. the 3D shape of certain RNA molecules look similar to enzymes
2. polypeptide linkages are catalyzed by riboenzymes
3. enzyme called reverse transcriptase in retroviruses catalyze synthesis of DNA from RNA
4. short naturally occurring RNA molecules catalyze polymerization of nucleotides in experiments
5. artificial riboenzyme developed that catalyzes assembly of short RNA into larger molecules that is the exact copy of itself

Question 28

Why would a membrane have been critical in the evolution of life?

Answer 28

because it allowed cells to compartmentalize/ concentrated and separate the internal from the external, maintaining a chemical composition different from the outside

Question 29

Why do fatty acids form a lipid bilayer around a liquid compartment in water?

Answer 29

because the hydrophobic tails want to touch and the hydrophilic tails are drawn to the water so it naturally creates the basics of a proto cell

Question 30

Explain what the first proto cell may have looked like.

Answer 30

A bilayer would form around a piece of RNA in water, but it would still allow small molecules to pass through like sugars and nucleotides, so that if the RNA was capable of self replication, other nucleotides could enter and be incorporated into more complex polynucleotides

Question 31

What is replication?

Answer 31

duplication of genetic material

Question 32

what is spontaneous generation?

Answer 32

creating life from inaniment objects/ nature

Question 33

what is the Miller / Urey experiment?

Answer 33

their hypothesis - organic chemical compounds can be generated under conditions similar to those that existed in the atmosphere of primitive earth

Step 1. Heat chemicals to form atmosphere of methane, ammonia, hydrogen, and water vapor,

Step 2. provide energy with electrical sparks (simulating lightning)

Step 3. Cool gases in the rain contains new compounds

Step 4. Collects and analyze condensed liquid