Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology Exam 2 > Chapter 9&10: Molecular Genetics > Flashcards

Chapter 9&10: Molecular Genetics Flashcards

(70 cards)

Start Studying
1
Q

What does it mean when DNA and RNA strands have polarity?

A

It means they have a 5’ end and a 3’ end. It defines the directionality. The phosphodiester bond will always link the 5 carbon of one deoxyribose to the 3 carbon of the next sugar. The 5’ end is connected to a phosphate group while the 3’ end is connected to a hydroxyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does molecular genetics concern itself with?

A

focuses on the macromolecules that carry genetic information, such as DNA, RNA, and proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does every nucleotide consist of?

A

A pentose sugar, a phosphate group and a nitrogenous base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Nucleosides

A

consist of just the nitrogenous base and the pentose sugar. NO PHOSPHATE GROUP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Remember

A

Nucleotides are added in the 5’ to 3’ direction. This means that new nucleotides are added to the 3’ end of the growing nucleic acid strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the difference in structure between deoxyribose sugar and ribose sugar

A

Deoxyribose sugar has one OH group on the bottom but ribose sugar has two OH groups on the bottom of the pentose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are purines

A

Include adenine and guanine. You can also think Pure as gold. They have a two ring structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are pyrimidines

A

These includes Thymine, Cytosine and Uracil. These have one ring structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why did scientists believe that proteins contained the genetic material instead of DNA?

A

1) must be diverse meaning having the capacity to code for many genes
2) Each gene must be able to code for highly specific function
Proteins are very diverse and have very specific functions (think of enzymes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Who discovered that DNA was actually what contained our genetic information?

A

Oswald Avery after Griffiths experiments. Eliminating DNA stopped the transfer of genetic information from the dead smooth cells to the rough cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a bacteriophage?

A

a virus that infects the bacteria by injecting its own DNA into the bacterial cell. The genetic material uses the cellular machinery to make copies of itself until the cell bursts and new copies of the virus is released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What did Chargaff discover ?

A

He knew that DNA was a polymer consisting of nucleotides that each had three components: a nitrogenous base, a pentose sugar and a phosphate group. he also noticed that DNA composition varied among species such as humans having more adenine composition compared to other species. He also noticed known as Chargaff’s rules that the amount of adenine is about the same as the amount of thymine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

DNA does enter the cell? Alfred and Margaret discoveries, need more elaboration

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What did James Watson and Francis Crick discover?

A
  • DNA is a double stranded helix with a uniform diameter. The nitrogenous bases are facing inwards towards each other.
  • It is a right handed helix
  • the outer edges of the nitrogenous bases are exposed in major and minor grooves which make them available to hydrogen bond with other proteins
  • They ultimately discovered the 3-D structure of DNA and discovered the ultimate structure of DNA
  • Them discovering the structure also allowed them to understand the function of DNA more
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the three models proposed by Francis and Crick?

A

1) Conservative model - when the DNA molecules are completely new and the parental strands remain completely intact.
2) Semi conservative model - DNA replication uses this model. The parent strand is used as a template for a new strand
3) Dispersive model - when DNA replicates itself, each resulting strand of both daughter DNA molecules has both old and new parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What did the Meselson - Stahl experiments find?

A

They found that DNA replication was semi-conservative. They did the experiments with the test tubes and isotopes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Replication forks

A

allow DNA replication to proceed in both directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are replication bubble rich in?

A

Adenine and Thymine bonds because they only have two hydrogen bonds between them which are easier to break

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the enzyme that is responsible for unwinding DNA at the replication fork

A

Helicase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Single stranded binding protein

A

stabilizes the single stranded DNA while DNA synthesis occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Topoisomerase

A

enzyme that relieves supercoiling ahead of the replication bubbles by unwinding and then rejoining the DNA strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

DNA polymerase II

A

the enzyme that catalyzes the synthesis of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In what direction does DNA polymerase II add nucleotides

A

From the 5’ prime end to the 3’ end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the leading strand

A

strand that occurs in one continuous motion as the replication fork expands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the lagging strand?
strand on the DNA that proceeds away from the replication fork in which DNA ligase has to join the Okazaki fragments together to form a single DNA strand
26
What is the difference between synthesis in DNA vs RNA?
DNA polymerase only adds nucleotides to a 3 carbon so if a 3 carbon is not there then DNA Synthesis cannot occur. However, RNA synthesis can start from scratch because they have an enzyme primase that adds an RNA primer of five to ten base pairs which allows replication to begin and then DNA polymerase I later replaces the RNA primer with DNA. DNA ligase glues the DNA fragments together
27
What is the function of primase
Sets down RNA primers to allow DNA synthesis to occur
28
What is the end replication problem?
refers to the fact that there is no way to replace the RNA primer at the 5 end of the daughter strand thats complementary to the lagging strand. DNA polymerase cannot replace the RNA primer with DNA at the end
29
What are telomeres?
nucleotide sequences that repeat several hundreds of times at the end of chromosomes. Prevent the erosion of important genes in the middle of the DNA
30
Telomerase
enzyme that catalyzes the lengthening of the telomeres in the germ line. It lengthens the telomeres on the PARENT STRAND allowing for the synthesis of additional DNA in the daughter strand. Is not at work in the somatic cells
31
Beadle and Tatum discovery
one gene code's for one enzyme. If a mutation results in the failure to produce an enzyme it could ruin a metabolic pathway that leads to the creation of an enzyme. -> has been modified to one gene for one polypeptide. each gene codes for a single polypeptide chain
32
What is the central dogma of molecular biology by Francis Crick?
It states that the flow of genetic information is from DNA to RNA to proteins
33
More than one codon can code for the same amino acid
34
The codons are read from the 5' to 3' direction
35
Each codon only codes for ONE amino acid
36
What is the start codon ?
Every protein begins with methionine. the start codon is always AUG. Protein synthesis cannot start until this part of mRNA is read
37
What is the stop codon?
There are three stop codons. UAA, UAG, UGA. These codons do not code for an amino acid
37
The NirenBerg-Matthaei experiment
found that certain codons code for certain proteins
38
What is transcription?
refers to the synthesis of RNA from genetic information contained in the DNA. In prokaryotes, it has three stages: initiation, elongation and termination.
39
RNA polymerase
an enzyme that catalyzes the synthesis of mRNA from DNA. it binds to a sequence on the template strand called the promoter sequence and starts to unwind the DNA
40
What are transcription factors?
these are proteins that recognize and bind to areas slightly upstream of the promoter sequence to help RNA polymerase bind to the promoter sequence and initiate transcription. RNA polymerase binds to the DNA transcription factor complex to form a transcript initiation complex
41
How are transcription factors different in prokaryotes?
In prokaryotes, the RNA polymerase automatically recognizes the promoter sequence and does not need transcription factors in order to bind to the promoter sequence
42
What is stage 2: Elongation
RNA polymerase is adding nucleotides to the 3' end of the growing RNA strand meaning it works in the 5' to 3' direction as usual, and it reads the template strand from the 3' to 5'. RNA polymerase does not touch the coding strand, and the coding strand is identical to the mRNA strand.
43
Unlike DNA polymerase, RNA polymerase does not require a primer
44
What is stage 3: Termination
Does not end at the stop codon but ends a short distance past the termination signal where the pre-mRNA is cleaved from the polymerase. The start and stop codon refers to the impact it has on TRANSLATION not transcription
45
What is post translational processing (in eukaryotes). What are the three important ways that pre-mRNA is enzymatically modified before being shipped out of the nucleus?
1) Addition of a 5' guanosine cap -> protects transcript from degradation and serves as recognition signal by ribosomes 2) Addition of a 3' poly-A tail -> added to the 3' end of the pre-mRNA. necessary for the export of mRNA from the nucleus to the cytoplasm and ensures mRNA remains stable during translation 3) Removal of introns
46
What is an intron?
a sequence of nucleotides that gets removed from the pre-mRNA and is never translated
47
Only exons are retained in the pre-mRNA and have the potential to be translated to a protein
Exons = expressed in the final mRNA and code for proteins
48
How are the introns spliced out and the exons joined together?
exons are joined together by spliceosomes. They cut out the introns and join the exons together forming the fully functional mRNA that is ready to leave the nucleus
49
Ribozymes
are RNA molecules that function as enzymes. They have a unique self-splicing process where certain introns are able to remove themselves
50
What are different ways that introns are beneficial?
They allow a single gene to code for a number of different proteins.
51
What is alternative splicing?
a single pre-mRNA transcript can be spliced in multiple ways producing different mRNA variants from the same gene. a single gene is able to code for a number of different proteins depending on which introns are left and which are taken out
52
What is the difference between prokaryotic and eukaryotic translation
Prokaryotic translation: all occurs in the cytoplasm. Messenger RNA is produced through transcription and then immediately translated into protein Eukaryotic translation: Pre-mRNA is modified to mRNA in the nucleus before being shipped out to the cytoplasm where translation occurs on ribosomes
53
What is translation?
the synthesis of polypeptides from information contained in the messenger RNA
54
What does transfer RNA do?
it physically links messenger RNA and amino acids together. Transfers amino acids from the cytoplasm to the ribosome and contains an anticodon
55
What is tRNA wobble?
occurs when a given tRNA anticodon can base pair with multiple codons that are different in the third position. This is due to the uracil in the wobble position being able to bond to adenine or guanine
56
Inosine
adenine in tRNA can bond to cytosine, adenine or uracil
57
What is the process of tRNA charging?
specific amino acids are attached to the correct tRNA via aminoacyl-tRNA synthetase.
58
There is one aminoacyl-tRNA synthetase for each amino acid
59
The mRNA binding site is located on the small subunit
60
what are the three different binding sites in the large subunit of the ribosome
A site -> where the charged tRNA molecule is bound to the ribosome P site -> where the amino acids keep attaching to the polypeptide chain E site -> the exit site where tRNA molecules go before they are released from the ribosome
61
What are the three major steps in polypeptide synthesis on the ribosomes. Think always that the mRNA is attached to the tRNA
1) Initiation -> the small subunit binds the mRNA at the 5' end. The small subunit and the large subunit attach to one another. The initiator tRNA is in the P site 2) The codon in the A site bind to the anticodon and the polypeptide in the P subunit and the amino acid in the A site ae joined together via a peptide bond that is catalyzed by the enzyme rRNA ribozyme. The polypeptide in the P subunit separates from the tRNA and the tRNA moves from the A site to the P site 3) Termination -> When the mRNAs stop codon reaches the A site, a release factor protein binds to the stop codon, hydrolyzing the bond between the tRNA in the P site and the last amino acid in the polypeptide
62
What is translocation
Its when the tRNA in the A site moves to the P site after the polypeptide chain has disengaged itself from the tRNA
63
What is the difference between ribosomes in the cytoplasm and ribosomes on the endoplasmic reticulum?
Ribosomes in the cytoplasm are responsible for creating soluble proteins and ribosomes on the ER are responsible for synthesizing endomembrane proteins and secreted proteins such as hormones
64
Protein targeting only occurs in Eukaryotes
65
Small nuclear RNA
a component of spliceosomes, that converts pre-mRNA to mRNA by splicing out introns
66
Direction of template read in DNA replication
3' to 5'
67
Direction of template read in transcription
3' to 5'
68
Direction of template read in translation
5' to 3'
69
RNA primer is only needed in
DNA replication

Biology Exam 2 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions