Chapter 10 DNA Replication and protein sythesis

Question 1

Briefly explain the history and work of Watson, Crick, Franklin, and Wilkins

Answer 1

Waston, crick and wilkins made the double helix and DNA
Frankilin used the x ray and photos of DNA

Question 2

Describe the structure of DNA including locations of covalent and hydrogen bonds, base pairing, and the major components of a nucleotide

Answer 2

A DNA molecule is composed of two strands. Each strand is composed of nucleotides bonded together covalently between the phosphate group of one and the deoxyribose sugar of the next. From this backbone extend the bases. The bases of one strand bond to the bases of the second strand with hydrogen bonds.
a double helix formed from two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs.
a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base.

Question 3

Compare DNA and RNA

Answer 3

DNA is Double, contaims nucletides made out of sugar of deoxyribose and has 4 bases which is ATGC.
Rna is single strand and sugar is ribose , hydrogen to itself and and pair itself also hadd 4 bases which is AUCG

Question 4

Describe mechanisms of DNA repair

Answer 4

(1)direct reversal of the chemical reaction responsible for DNA damage, and (2) removal of the damaged bases followed by their replacement with newly synthesized DNA.

Question 5

Understand what the consequences are if the DNA mutation occurs in a somatic cell vs. a germline cell

Answer 5

You can’t inherit somatic mutations because if you do it would result cancer cell or the cell would die.
Germs cell mutation can be passed to an organism’s offspring

Question 6

Explain the central dogma

Answer 6

Centrol dogma: DNA encodes for RNA
RNA to proteins

Question 7

Describe how eukaryotic mRNA is processed

Answer 7

1) 5’ nuclotide cap is added
2) poly A tail is added to 3’ end about 200 adenines
3) Splicing occurs

Question 8

Decsribe the difference inheritable and nonhertiable occur in

Answer 8

hertiable sex cells and non in somatic cells

Question 9

Describe the genetic code and how the nucleotide sequence determines the amino acid sequence of a protein

Answer 9

the DNA sequence is interpreted in groups of three nucleotide bases, called codons.Each codon specifies a single amino acid in a protein.

Question 10

Discuss why cells do not express all of its genes all of the time

Answer 10

because these cells have distinct sets of transcription regulators and conserves energery and space

Question 11

Describe how prokaryotic gene expression occurs at the transcriptional level

Answer 11

Due to the lack of a nucleus also prokaryotes.
Prokaryotes control gene expression by regulating transcription in the nucleus, and also by controlling the RNA levels and protein translation present outside the nucleus.

Question 12

Understand that eukaryotic gene expression occurs at the epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels

Question 13

What is the role of Helicase?

Answer 13

Helicase: Unwinds DNA helix, breaking hydrogen bonds or separate double-stranded DNA into single strands allowing each strand to be copied

Question 14

What is the role of DNA Polymerase?

Answer 14

DNA Polymerase- Adds nucleotides one-by-one ro match parent strand building a new strand 5’ to 3’. adding complementary nucleotides to one of the template strands of the original DNA.

Question 15

What is the role of DNA ligase

Answer 15

DNA Ligase- acts as a glue during DNA replication, ensuring that the lagging strand is properly synthesized by connecting the Okazaki fragments

Question 16

What is the role RNA polymerase

Answer 16

RNA Polymerase-multi - unit enzyme that sythesiszes RNA molecules to form a templates of DNA through process called transcription and or combines both proteins.

Question 17

What is the role of Transfer RNA (tRNA)

Answer 17

Transfer RNA (tRNA)-carry animo acid to the site of protein sythesis in ribosome

Question 18

What is the role of messeger (mRNA)

Answer 18

Messenger(mRNA)-coded from DNA gene

Question 19

Role of the Ribosomal RNA (rRNA)

Answer 19

Ribosomal RNA (rRNA)- combined with proteins to form ribosome

Question 20

What is the structure of nucleic acids?

Answer 20

Nucleis acids structure is DNA and RNA

Question 21

What four nitrogenous bases are found in DNA? Which form pairs? What makes up the structure of the DNA backbone?

Answer 21

Four bases: Adenine (A), Guanine (G), Cytosine (C) and Thymine (T).
Form Pairs: A=T and C=G
The strcture of DNA backbone is phospahte and deoxyribose groups covalent bond to form the “backbone”.

Question 22

What four nitrogenous bases are found in RNA? Which form pairs?

Answer 22

4 Nitrogenous bases: Adenine (A), Guanine (G), Cytosine (C) and Uracil (U).
Pairs are: A=U, C=G

Question 23

What does antiparallel mean in terms of DNA structure?

Answer 23

Antiparellel= Opposite direction like 5’ to 3’, 3’ to 5’

Question 24

What are the steps of DNA replication? Which enzyme carries out each step?

Answer 24

Main stages:
1)helicase unzwinds the DNA helix breaking hydrogen bonds
2)Replication forks are formed as DNA opens bubbles meaning Eukaryotes linears with bond between complimentary base pair that later on becomes seperated.
3)RNA primers are added by RNA primase to both strands
4)DNA polymerase adds nucleotides one by one to match parent strand biulding a new strand 5’ to 3’ called leading strand
5) After the RNA primer is laid at the replication fork, DNA polymerase binds to lagging strand coding away from the fork forming the Okazaki fragment.
6) DNA polymerases replace RNA primers with DNA nucleotides
7)DNA ligase bind the gaps in DNA including Okazaki fragments
8)Concludes as both original strands are bound to their new complementary strands.

Question 25

What is the difference between the 3’ and 5’ ends of a DNA strand? In which direction does DNA replication occur?

Answer 25

The 3’ end has a hydroxyl and nuclotides are added and a group on the deoxyribose sugar, whereas the 5’ end has a phosphate group lagging strand.

DNA direction is in 5’ to 3’

Question 26

What are telomeres? What is their role?

Answer 26

Telomere- Repetitive sequences at end of linear chromosomes.
Role of telomere is
1. doesen’t codes for genes,
2.prevent DNA damage
3.fusion of chromosmes, shortened with each round of DNA replication

Question 27

How is DNA replication different in prokaryotes compared to eukaryotes?

Answer 27

Prokaryoutes: One circular chromosomes
Very fast
One single orgin of replication
Helicase, DNA polymerase, and ligase operate the same just faster
Higher mutation faster

Eukaryotes: Helicase, DNA polymerase, and ligase operate the same but very slow
many linear chromosomes

Question 28

Is a mutation always bad? Explain. Where must a mutation occur in order to be passed on to the next generation?

Answer 28

Mustation can be good, bad and neautral and depending on their context or location.
Mutation occur in egg and sperm to pass the next generation

Question 29

What are the differences between the leading and lagging strands?

Answer 29

Leading strand is countiusly coded by DNA polymerase follwoing helicase toward repllication fork.
Lagging strand is built in pieces away from the replication fork.

Question 30

What are the steps of transcription?

Answer 30

1)Gene promoter is recognized on the DNA prior gene code
2)RNA polymerase binds and unwinds DNA
3)RNA polymerase matches RNA nucleotides to DNA template stand
4)RNA polymerase moves along a template strand building RNA 5’ to 3’
5)Last step RNA polymerase reaches the terminator and seperates from DNA and mRNA is released

Question 31

How is RNA processed in eukaryotes?

Answer 31

Euakryotes must first process to mRNA and trasnport it to the cytoplasm.

Question 32

How can an organism produce a greater number of different protein types than it has genes in its genome?

Answer 32

Protein number can exceed gene number in eukaryotes, in part because cells can produce different RNA variants from the same genes by “alternative splicing”,

Question 33

What are the steps of translation?

Answer 33

Initiation:complex forms
-Small subunit of ribsome finds the start codon (AUG) on mRNA
-1st tRNA with the anticodon (UAC) interacts with codon and brings the corrresponding (methionine) to P site.
-Large subunit of ribosome caps off the complex
Elognation:
- Ribosome moves along mRNA
-2nd tRNA enter the A site with next anticoden and animo acid
-Animo acid 1 forms peptide bond with animo acid 2
-1st tRNA enters
Translation is terminated
Protein is released
Termination:
-A stop codon arrives in the A site
-eukaryotes rough ER asiste
-prokaryotes don’t involve bc they don’t have a ER

Question 34

How is transcription and translation different in prokaryotes compared to eukaryotes?

Answer 34

In Transcription prokaryotes, the mRNA is translated by the ribosomes as it being created and Euakryotes must first process mRna and transport to cytoplasm.
In translationn In eukaryotes the rough endoplasmic reticumlum asisits(help). Prokaryotes don’t involve becasue they don’t have a endoplasmic reticulum.

Question 35

What are the different sites within a ribosome? What events of translation occur within each site?

Answer 35

Ribosome has 3 compartment- A, P and E site
A site accepts an incomming tRNA bound to animo acid
P site holds a tRNA that carries a growing polypeptide
E site which holds the decylated tRNA before it leaves the ribosome

Question 36

What is the genetic code and how does it work?

Answer 36

Genetic code is the relationship between the nuceotides sequence and the matching of animo acids
Hydrogen bonds between DNA nucletide bases

Question 37

What are the different types of mutations and the effects of each?

Answer 37

Point mutation- One single nucletide changed in sequence
Heritable mutations- found in gametes and pass on the next generation and may affect a whole populations.
Nonheritable mutations- Affect the individual but not passed to the next generation
will not afffect a whole population

Question 38

How are genes regulated in prokaryotes and eukaryotes?

Answer 38

Prokaryotic transcription and translation occur simultaneously in the cytoplasm, and regulation occurs at the transcriptional level.

Eukaryotic gene expression is regulated during transcription and RNA processing, which take place in the nucleus, and during protein translation, which takes place in the cytoplasm.

Question 39

Transcription/Translation Practice:

1) If a codon contains the nucleotides ACU what must the anticodon be?

Answer 39

UGA

Question 40

2) Write the complement for the DNA sequence below (including directionality)

5’-ATCGGCG-3’

Answer 40

3’-TAGCCGC-5’

Question 41

3) Write the mRNA transcript for the DNA sequence below:

TACGTCCAT

Answer 41

AUGCAGGUA

Question 42

4) Translate the mRNA sequence from number 3.

TACGTCCAT

Answer 42

AUGCAGGUA

Met-Gln-Val

Question 43

5) The DNA sequence from #3 has a mutation (highlighted in yellow). Transcribe and translate this new sequence. Would this mutation affect the polypeptide?

TACGTCCAC

Answer 43

AUGCAGGUC

Met-Gln-Val

It would not affect the polypeptide since the same amino acids are produced during translation. This would be an example of a silent mutation.