DNA Structure and Replication, Protein Synthesis, Mutations & Genetic Engineering

Question 1

State Stargaff’s Rule

Answer 1

The amount of 4 bases are not equal
Bases are present in a characteristic are not a equal ratio
A=T and G=C (All in percentages)

Question 2

Summarize Rosalind Franklin’s contribution to determining the structure of DNA

Answer 2

She used X-ray photography to analyze the structure of DNA and found that it is a helix w/ 2 repeating patterns. She found that nitrogen bases were on the inside and the sugar-phosphate was on the outside

Question 3

Describe the double helix structure DNA discovered by Watson and Crick

Answer 3

The discovered it was like a twisted ladder. The handrails on the outside are the sugar-phosphate backbone. The rungs or steps of the ladder are the nitrogen bases that are arranged in complementary pairs (A-T and C-G). The two stands are NOT IDENTICAL and they are ANTI-PARALLEL (they run the opposite of one another- one strand is pointed up and the other down

Question 4

Describe the antiparallel strands (twisted ladder)

Answer 4

The 5’ to 3’ ends run in opposite directions on each strand of nucleotides in a double strand DNA molecule the 5’ end points up strand and down the other

Question 5

Compare DNA to RNA- sugar, nitrogen bases, # of stands and where it occurs

Answer 5

DNA: Deoxyribose, A-T and C-G, two strands, nucleus
RNA: Ribose, A-U and C-G, one stand, cytoplasm

Question 6

Define gene:

Answer 6

A functional sub-unit of DNA that directs the formation of a protein (or polypeptide) molecule

Question 7

Define genome:

Answer 7

is all of the DNA in each organism’s cells. It includes genes and non-coding sequences of DNA that do not direct the information of a protein

Question 8

What is the first step for semi-conservative replication?

Answer 8

1. Two stands of template DNA before replication in S Phase of interphase

Question 9

What is the second step for semi-conservative replication?

Answer 9

2. The DNA unwinds due to the helicase enzyme cutting the H bonds between matching nitrogen bases and the DNA polymerase enzyme adds in matching new bases to the template strand

Question 10

What is the third step for semi-conservative replication?

Answer 10

3. The ligase enzyme glues the DNA up to make two daughter strands: half old and half new

Question 11

What does helicase do?

Answer 11

It breaks the weak H bonds between nitrogen bases to unwind the DNA molecule

Question 12

What does DNA polymerase do?

Answer 12

Adds complementary bases to the template DNA to make a new stand

Question 13

What does Ligase do?

Answer 13

Glues up the bases on the newly made DNA strands to join them together

Question 14

In what way is the structure of a protein related to the genetic code?

Answer 14

The sequence (order) of the base pairs in a DNA molecule, the genetics code, decides the sequence of amino acids in a protein

Question 15

Summarize the steps in Central Dogma or Transcription and Translation:

Answer 15

Transcription (Step 1): Occurs in the nucleus. Genes on DNA are made into an mRNA copy
Translation (Step 2): Occurs in the cytoplasm at a ribosome: the sequence of bases on the mRNA molecule determines the sequence of amino acids in a protein

Question 16

Define Codon:

Answer 16

A set of three bases that codes for an amino acid or a stop codon. 3 bases= 1 codon

Question 17

What is a redundant characteristic of a genetic code?

Answer 17

More than one codon can code for the same amino acid. Only 3 codons do not code for any amino acids (they code for stop codons instead)

Question 18

What is a continuous characteristic of a genetic code?

Answer 18

There is no spaces, punctuation or overlap in the genetic code

Question 19

What is a universal characteristic of a genetic code?

Answer 19

All living organisms build proteins w/ the same genetic code

Question 20

Describe the role of RNA polymerase in transcription?

Answer 20

It unravels a section of the DNA that is to be made into mRNA. It works in the 5’ to 3’ direction to add complementary mRNA bases to the template DNA strand that is being transcribed

Question 21

Define anti-codon

Answer 21

A stretch of 3 nucleotides found on the tRNA molecule that is complementary to the mRNA codon. If the mRNA codon is CGA then the anticodon is GCU

Question 22

What is a mutaiton?

Answer 22

A permanent change in the genetic material (base sequence of DNA) of an organism- it is inheritable

Question 23

How can mutations be inherited?

Answer 23

They are copied during DNA replication (S phase of interphase) and passed onto daughter cells

Question 24

What is a mutagen?

Answer 24

Substance/ event that causes an increased rate of mutation in an organism

Question 25

What is a carcinogen?

Answer 25

A cancer causing factor (mutagens associated with one or more types of cancer)

Question 26

How can mutations lead to: cancer?

Answer 26

Mutations accumulate within cells and combinations of mutations can lead to cancer

Question 27

How can mutations lead to: Genetic variation?

Answer 27

Accumulation of mutations over time provides diversity (variation) and gives different characteristics of organisms

Question 28

In which two parts of a cell is DNA found, besides the nucleus?

Answer 28

Mitochondria and chloroplasts

Question 29

How are mitochondrial and chloroplast DNA different from nuclear DNA?

Answer 29

- Slightly different genetic code | - Can replicate, transcribe/ translate independently of nuclear DNA

Question 30

Why is mitochondrial DNA identical to the mtDNA of your mother, not your father?

Answer 30

- At fertilization the egg contributes to the cytoplasm of the zygote,sperm from dad does not contribute any cytoplasm - mtDNA/ mitochondria are found in the cytoplasm = it is inherited from mom

Question 31

What is genetic engineering?

Answer 31

Recombinant DNA technologies: manipulating genetic material to alter genes and blend plants, animal and bacterial DNA together

Question 32

What is recombinant DNA?

Answer 32

Genetic material that comes from different sources

Question 33

What are restriction enzymes? (Also called restriction endonuclease)

Answer 33

Cleave (cut) DNA at specific nucleotide sequences. They are like molecular scissors

Question 34

How are restriction enzymes used in genetic engineering?

Answer 34

They cut DNA at specific recognition its, which produces a "sticky end"- this end can be joined onto another strand of DNA to form base pairs

Question 35

What is the role of DNA ligase in genetic engineering?

Answer 35

Ligase splices or joins pieces together to make a recombinant DNA molecule

Question 36

Describe how restriction enzymes and DNA ligases work together in recombinant DNA technology?

Answer 36

Restriction enzymes act as molecular scissors to cut DNA from one organism and DNA ligase joins the DNA strands together

Question 37

What is a gel electrophoresis?

Answer 37

A method used to separate molecule (like DNA) according to mass, charge and size

Question 38

What is a DNA fingerprint?

Answer 38

A pattern of bonds that shows the fragments of DNA in a sample (longest fragments do not move far-> smallest fragments move furthest)

Question 39

What are two real life uses for DNA fingerprints?

Answer 39

Forensics: match suspect to crime scene | Paternity test: child have half DNA from mom and half from dad

Question 40

What process is the polymerase chain reaction (PCR) process like?

Answer 40

DNA replication

Question 41

What is a transgenic organism (genetically modified organism or GMO)?

Answer 41

An organism who's genetic material includes DNA from different species