unit 5 molecular genetics

Question 1

What is the defintion of genetic transformation and how does it work?

Answer 1

The information for the traits/features of an organism is contained in the nucleic acids
If another organism receives these nucleic acids, it may express the same traits as the original

Question 2

What was Rosalind Franklin’s contribution to DNA research/

Answer 2

produced the X-ray diffraction photograph implying DNA’s double helix structure

Question 3

what was griffith’s contribution to DNA research?

Answer 3

proved that changes in the genotype and phenotype of bacteria are due to the assimilation of external DNA by the cell

Question 4

what was Avery’s contribution to DNA research?

Answer 4

verified Griffith’s theory that changes inthe genotype are due to assimilation of external DNA
- proved that DNA was responsible for the GENETIC TRANSFORMATION of bacterial cells

Question 5

what was Hershey-Chase’s contribution to DNA research?

Answer 5

determined that the DNA and not the proteins of a bacteriophage is injected into a host bacterial cell during infection

Question 6

what are the 3 key roles of DNA?

Answer 6

-storage of genetic information: the instructions needed for an organisms growth, development, and function, carried in codons of nitrgoenous bases that determine traits.

replication for cell division: occurs during the s phase of interphase

protein synthesis: DNA provides the instructions for making proteins. This occurs during two processes: transcription (DNA to mRNA) and translation (mRNA to protein)

Question 7

list the chemical components of DNA

Answer 7

The chemical components of DNA include:

Deoxyribose Sugar – A five-carbon sugar that forms part of the backbone of DNA.
Phosphate Group – Connects to the sugar to form the sugar-phosphate backbone.
Nitrogenous Bases – The four bases that store genetic information:
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
These components combine to form nucleotides, which are the building blocks of DNA.

Question 8

what researchers in chronological order verified the structure of DNA?

Answer 8

Chargaff, Pauling, Wilkins+Franklin, Watson+Crick

Question 9

what was Chargaff’s contribution to the verification of the structure of DNA?

Answer 9

determined that the ration of A:T and C:G were equal

Question 10

what was Pauling’s contribution to the verification of the structure of DNA?

Answer 10

proposed the heliacal structure of DNA

Question 11

what was Wilkins+Franklin’s contribution to the verification of the structure of DNA?

Answer 11

proved through the x-ray diffraction photograph that DNA had a double helix structure

Question 12

Watson+Crick

Answer 12

publicsehd the paper “ the molecular structure of nucleic acids.”
Deduced that the sugar and phosphate groups of the nucleotides formed the backbones of the DNA molecule and the nitrogenous bases form pairs that compose the ruigs of the double helix

Question 13

what is the difference between prokaryotes nad eukaryotes in DNA replication?

Answer 13

prokaryotes: DNA replication start at one point and moves in two directions until the whole DNA is copied .THis is because prokaryotes have a single, circular DNA strand.

Eukaryotes: DNA replication start at many points along the DNA and occurs concurrently . This takes longer!

Question 14

what was miescher’s contribution to the discovery of DNA being the source of all genetic material?

Answer 14

the first to isolate nucleic acids

Question 15

what was Griffith’s contribution to the discovery of DNA being the source of all genetic material?

Answer 15

discovered the source of genetic information in bacteria through the pneumonia mice experiment.
-discovered bacterial transformation, which caused him to determine that changes in the genotype and phenotype are due to the assimilation of external DNA by the cell

Question 16

what was Avery’s contribution to the discovery of DNA being the source of all genetic material?

Answer 16

Verified Griffith’s protocol and determined that DNA was responsible for the genetic transformation of the bacteria cells

Question 17

What has hershey-chase’s contribution to the discovery of DNA being the source of all genetic material?

Answer 17

Determined that the DNA and not the proteins of a bacteriophage, a virus, is injected into a host bacterial cell during infection

Question 18

what molecule type is DNA?

Answer 18

a nucleic acid and polymer

Question 19

the monomer of the polypeptide DNA?

Answer 19

nucleotide

Question 20

what is the composition of a nucleotide in DNA? what is the composition of a nucleotide in RNA?

Answer 20

DNA: deoxyribose sugar, nitrogenous base, phosphate group

RNA: ribose sugar, nitrogenous base, phosphate group

Question 21

what are purines?

Answer 21

type of nitrogenous base, including adenine and guanine

Question 22

what are pyrmidines?

Answer 22

type of nitrogenous base, including thymine, cytosine, and uracil

Question 23

What is base pairing?

Answer 23

-the pariing of purines and pyrimidines that MUST occur for the double helix to form, because they form hydrogen bonds

Question 24

what are the DNA levels of organization?

Answer 24

DNA-Gene-Chromosomes-Genome

Question 25

What does semiconservative mean in the context of DNA replication?

Answer 25

it means that each daughter cell gets one strand of the original DNA and one strand of the replicated DNA?

Question 26

when does DNA replication occur?

Answer 26

during the S phase of interphase

Question 27

when does transcription occur?

Answer 27

Techincally can occur during any phase of interphase, but mostly occurs during G1 and G2

Question 28

What are the steps of DNA replication?

Answer 28

1. Helicase unwinds/unzips the DNA double helix by breaking the hydrogen bonds between the nitrogenous bases 2. DNA polymerases continuously replicate the leading strand using free nucleotides in the 5’-3’ direction. 3. The lagging strand is synthesized discontinuously in segments with the aid of DNA polymerases. The lagging strand is synthesized in the opposite direction of the leading strand. 4. DNA ligases induce the covalent bonding of the sugar phosphate backbone in the segments of the lagging strand.

Question 29

what is DNA ligase and what is it used for? when

Answer 29

DNA ligase is an enzyme that "glues together the gap" between the fragments of synthesized DNA on the lagging strand (IN THE 3'-5' direction - IT DOES THIS BY SEALING BREAKS IN THE SUGAR-PHOSPHATE BACKBONE by inducing polar covalent bonds - NOT NEEDED ONTHE LEADING STRAND BECAUSE IT CAN BE CONTINUOUSLY COPIED - used after step 3 of DNA replication

Question 30

in which direction is the leading strand? in which direction nis the lagging strand? WHY IS THIS IMPORTANT?

Answer 30

-dna can only be read ( and replicated) along the 5'-3' direction! - this is why the lagging strand of DNA is replicated in fragments

Question 31

what kind of bonds are formed in the sugar-phosphate backbone?

Answer 31

polar covalent bonds

Question 32

What are the steps of DNA transcription in prokaryotes? what about in eukaryotes?

Answer 32

prokaryote: DNA--> mrna transcription--> translation eukaryotes DNA--> pre-mrna transcription-->mRNA processing--> translation

Question 33

RNA vs DNA

Answer 33

Single helix vs. double helix Ribose sugar vs. deoxyribose sugar Uracil vs. thymine

Question 34

what is the function of mRNA?

Answer 34

carries information specifying amino acid sequences of proteins from DNA in the nucleus to the ribosome in the cytoplasm (these are the CODONS of TRANSLATION)

Question 35

what is the function of tRNA?

Answer 35

: Carries amino acids to the ribosome for protein synthesis. (these are the ANTICODONS of translation)

Question 36

what is a gene?

Answer 36

a large DNA sequence containing many codons.A gene is a segment of DNA that carries instructions for making a protein or a functional RNA molecule

Question 37

what is the function of ribosomal RNA?

Answer 37

a type of RNA that forms a key structural and functional part of ribosomes, the cellular machinery responsible for protein synthesis. It helps read mRNA, correctly positions tRNA, and catalyzes the formation of peptide bonds between amino acids, ensuring proper protein assembly.

Question 38

How does transcription occur?

Answer 38

RNA polymerase unwinds the DNA double helix and adds free RNA nucleotides to the 3’-5’ strand of DNA(the gene) creating an RNA transcript (pre-MRNA)

Question 39

what is the RNA transcript the same as?

Answer 39

-pre-MRNA in eukaryotes and MRNA in PROKARYOTES

Question 40

wht is RNA processing and in what cells does it occur?

Answer 40

-RNA processing is when EUKARYOTIC cells edit the initial RNA transcript (aka, PRE-MRNA IN EUKARYOTES) - IN this process, introns are removed and exons are spliced together to form the final mRNA transcript!

Question 41

what are introns?

Answer 41

the parts of the pre-mRNA that contains non-coding DNA.

Question 42

what are exons?

Answer 42

he parts of the pre-mRNA that contains the coding DNA.

Question 43

what are the steps of the process of translation?

Answer 43

1. The small subunit of the ribosome (aka, RRNA) binds to the mRNA transcript to begin translation -tRNA ANTICODONS begin to matchup with the complementary codons from the mRNA transcript -Each tRNA carries an amino acid which is peptide bonded to the newly created amino acid chain

Question 44

what are mutations?

Answer 44

- HERITABLE changes in genetic information

Question 45

What are point mutations

Answer 45

Point mutations; (substitution) → one change in DNA template, only one mRNA codon is shifted -substitutions usually only affect one AA or may have no effect at all

Question 46

what is a missense mutation?

Answer 46

-a type of point mutation (substitution) that changes the amino acid produced

Question 47

what is a silent mutation and why does it occur?--

Answer 47

-a type of point mutation that does not change the amino acid -occurs because of the WOBBLE POSITION (the last nucleotide in a codon can be changed bc there are many different combinations for the same amino acid (but only the last codon can be changed))

Question 48

what is a nonsense mutation

Answer 48

changes the amino acid to "stop," which leaves it malformed and therefore dysfunctional

Question 49

What is a frameshift mtuation?

Answer 49

insertion or deletion) → all mRNA codons are shifted

Question 50

what are the effects of frameshift mutations on the cell?

Answer 50

-can change every AA that follows the point of the mutation -insertions or deletions can alter a protein so much that it is unable to perform its normal functions

Question 51

what is the definition of a harmful mutation?

Answer 51

ones that dramatically change proteins structure or gene activity

Question 52

what is the definition of helpful mutations?

Answer 52

ones that may produce proteins with new or altered functions that can be useful to organisms in different or changing environments

Question 53

what are mutagens and what are their categories?+examples

Answer 53

chemical or physical agents in the environment that cause a mutation chemical mutagens - certain pesticides, environmental pollutants, etc. -physical mutagens - forms of radiation like X-rays and UV light

Question 54

why are mutagens so dangerous?

Answer 54

If these agents interact with DNA, they can produce mutations at high rates, increasing the chance of cancer

Question 55

in what direction do enzymes such as dna/rna polymerase read DNA? WHY?

Answer 55

v enzymes like DNA polymerase and RNA polymerase always read their template strand in the 3' to 5' direction so they can build a new complementary strand in the 5' to 3' direction.