Lab 3 Molecular Bio Flashcards Preview

Bio Lab > Lab 3 Molecular Bio > Flashcards

Flashcards in Lab 3 Molecular Bio Deck (35)
Loading flashcards...

What is the transcription start point



What is the termination sequence



What is the template strand



What is the coding strand



Name two diff methods for making copies of sequence of DNA. Which would u choose for amplifying DNA.

Polymerase chain reaction and Sangar sequencing.
PCR method to amplify because technique allows us to amplify a small sample of DNA, creating thousands to millions of copies of that DNA sequence. Gives a usable amount for testing.


Briefly describe how u could use restriction endonuclease enzymes and gel electrophoresis to find if blood came from Danny

After amplifying blood from suspect's mouth using PCR, use a specific restriction enzyme that cuts DNA into specific fragments. Then use gel electrophoresis to analyze fragments. Gel electrophoresis separates fragments into bands based on molecular size. Repeat process with found blood and compare two samples. No two people have same sequence, if identical, it would suggest the same person.


Have u discovered hamster killer allele (i.e. will everyone who has particular DNA sequence kill hamsters)

No. Allele can be dominant or recessive. If recessive can be masked in one generation. Traits are also affected by environmental factors.


Describe steps to determine which protein produced by DNA sequence.

Take restriction endonuclease enzyme and use them to cut up DNA sequence into fragments. Take fragments and place in bacterial plasmids. Bacterial plasmids act as vectors for DNA fragments. The recombinant DNA mixture now placed into E. coli bacteria cells and bacteria will begin to produce protein specified by the foreign genes.


What colour are phosphorous atoms. Defend answer.

Purple. Phosphorous bonds to 5' carbon of sugar.


What colour nitrogen atoms. Defend answer.

Blue. Nitrogen bonds to 1' carbon of sugar.


What colour carbon atoms. Defend answer.

Black. Deoxyribose sugar contains 5 carbon atoms bonded to each other, 5 black atoms bonded in a pentagon representing deoxyribose sugar.


What colour o2 and hydrogen atom. Defend.

Oxygen is red. Hydrogen is white. Oxygen atom bigger.


What colour is phosphate group

Purple and 4 red


What colour is deoxyribose sugar

Black, red, white


What colour nitrogenous base

Blue and black and white*


How tell apart purine from pyrimidine base

Pyrimidine base is 6 membered single ring with 2 nitrogens and 4 carbons. Inc. (Cytosine, thymine, uracil)
Purine base is 9 membered double ring with 4 nitrogens and 5 carbons. Inc. (Adenine, Guanine)
Also adenine has no oxygen.


Why purines never bond with each other and pyrimidines never bond together.

Structure would be too large and exceed the width of DNA molecule backbone. For DNA molecule to be functional, cannot be differences in width throughout molecule. Therefore, necessary for larger purine to bond to smaller pyrimidine so resulting structure remains within dimensions of DNA molecules.


How to tell apart base pairs

Tell apart purine and pyrimidine because purines have two bonded carbon groups, pyrimidine has one. Adenine bonded with NH2, guanine bonded with double bonded O, thymine bonded with double bonded O, cytosine bonded with NH2


Why adenine doesn't bind with cytosine and thymine doesn't bind with guanine.

Dont bind as strongly. C and G have 3 H bonding sites to form 3 H bonds. T and A have 2 H binding sites to make 2 H bonds. If T with 2 H bond sites and G with 3 H bond form bond, one leftover site in molecule; leads to the instability of bond


Within single DNA strand how individual nucleotides joined together

Phosphodiester bond. Phosphate of one nucleotide and 3' sugar of other.


How are two DNA strands joined together

Hydrogen bonds


Do ends of two DNA strands look exactly same on DNA model

No, one goes from 5' to 3' and another 3' to 5'. 5' ends.


What is gene expession

Describes how DNA-coded info from one gene is transcribed onto RNA and then translated into polypeptide that cell needs.


What do histones do

Neutralize and condense DNA into chromatin


How do restriction endonuclease enzymes work

Each restriction enzyme only cuts DNA at restriction sites with correct sequences of bases. If mutation changes just one letter in restriction site, enzyme will no longer cut at mutated site


Describe parts of DNA double-helix

Two strands of polynucleotide.
Each strand consists of, a phosphate group, a nitrogenous base (either A, T, C or G ) and a 5 carbon deoxyribose sugar

The two nucleotides join by hydrogen bonds between the matching bases (complimentary base pairing)


Describe gene expression

During initiation of transcription, proteins called transcription factors must bind to promoter region of DNA, which includes the TATA box. RNA polymerase II now can bind, forming an transcription initiation complex.
During elongation of transcription, RNA polymerase II reads DNA template strand and builds complementary RNA strand. RNA strand grows by addition of nucleotides to its 3' end.
During termination of transcription, RNA polyermase II reaches termination site and the RNA transcript is released from template. The RNA strand created is called pre-mRNA.
Noncoding regions called introns of pre-mRNA are removed and the remainder coding regions, called exons, are joined together, thus forming mRNA. The mRNA leaves the nuclear envelope into the cytoplasm for translation.
Small ribosmomal subunit finds AUG start codon. First tRNA binds to ribosome at P site, subsequent tRNA's bind at A site. Completmentary tRNA carrying amino acid binds to start codon. Start codon codes for methionine. Then large ribosomal subunit binds to form translational initiation complex. Anticodon of tRNA and codon on mRNA match up. First tRNA's moves left to E site, and its amino acid is transferred to P site. First tRNA without amino acid leaves E site and new tRNA with new amino acid comes to A site. When stop codon arrives at P site, translation is terminated.


What are enzymes

Proteins (sometimes nucleic acids) that increase rate of chemical reactions by acting as catalysts to lower action energy


What factors affect rate of enzyme-catalyzed reaction

Temperature, pH


What is competitive inhibition

Specific inhibitor molecule binds to active site of enzyme, decreasing reaction rates by competing w/substrate for enzyme's active site.