BiO181 Exam 2

What are the major components of the bases in a nucleotide?

Nitrogen

Single or double carbon ring

The covalent bond that joins two amino acids is called a _______ bond.

peptide

What are the three major structural components of an amino acid?

Side chain (R group)

Amino group

Carboxyl group

Which of the following statements is true about adenine and guanine?

They consist of two fused rings of C and N atoms.

They are purine bases.

Which are pyrimidine bases found in DNA?

Thymine

Cytosine

RNA molecules contain what type of sugar?

ribose

What base pairs are found in DNA?

Adenine-thymine

Cytosine-guanine

What does RNA contain?

Uracil

Ribose

Guanine

Cytosine

Adenine

4 Bases in RNA?

Uracil

Cytosine

Guanine

Adenine

The amino acid sequence of a polypeptide is called the ___ structure

primary

Carboxyl group

What part of the amino acid is circled?

What are the 4 bases of DNA?

Adenine, Thymine, Guanine, Cytosine

What are the three basic components of a nucleotide?

Phosphate group, Sugar, Base

What type of bond is responsible for the base pairing between two strands of DNA in the double helix?

Hydrogen Bond

In a DNA double helix, adenine on one strand is paired to ______ on the other strand via ______ hydrogen bonds.

thymine ; two

For a molecule to serve as the genetic material, it must meet the following key criteria:

information, replication, variation, transmission

RNA differs from DNA in that RNA contains the base ___, and does not contain the base ___

uracil, thymine

A linear DNA strand contains two ends: the 5 prime end has a free ______ group, while the 3 prime end has a free ______ group.

P, OH

Which amino acid is responsible for the formation of disulfide bonds?

Cysteine

The terminator is a site in the DNA where the ___ of a gene ends

transcription

What are the stages of transcription?

initiation, elongation, termination

ranscription begins at a site in DNA called the

promoter

What is synthesized during the elongation stage of transcription

RNA

How is the 5' end of a eukaryotic mRNA modified?

a cap is added to it

How is the 3' end of a eukaryotic mRNA modified?

A poly A tail is added to it

introns

a segment of a DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes.

exons

Coding segments of eukaryotic DNA.

what is the spliceosome complex's function and what does it include?

A large complex made up of proteins and RNA molecules that splices RNA by removing of introns and connecting exons

Chargaff's Rule

A=T and C=G

antiparallel configuration

The opposite arrangement of the sugar-phosphate backbones in a DNA double helix.

Connected with hydrogen bonds

Pyrimidines

cytosine, thymine, uracil

Purines

Adenine and Guanine

polymerization

putting a polymer together using a dehydration reaction

Sugar used in RNA

ribose

Sugar used in DNA

deoxyribose

What is the difference between DNA and RNA

DNA is double stranded and RNA is single stranded

DNA stores and transfers genetic information, RNA codes

what bond connects one nucelotide to the next

phosphodiester bonds

non-polar amino acids

hydrophobic

polar amino acids

hydrophilic

charged animo acids

hydrophilic

What defines the function of a protein

structure

What is a denatured protein

a protein that has lost its shape and function by being unfolded

N-terminus

amino end

C-terminus

carboxyl end

what is a peptide bond?

covalent bond between the carboxyl group and amino group

primary structure

peptide bonds

specific order of amino acids- unique to every protein

secondary structure

Hydrogen bonds form spirals ((a helix) or pleats (beta)

Tertiary Structure

additional folding of the polypeptide forms a 3D structure

What are the 5 types of interactions in a tertiary structure?

Disulfide bonds (covalent bond)

Hydrogen bonds

Ionic bonds

Non-polar interactions

Vander Waals interactions

disulfide bond in tertiary structure

covalent bond between 2 cysteine amino acids

ionic bond in a tertiary structure

between charged R-Groups

hydrogen bonds in tertiary structure

between polar R-groups

non-polar interactions in a tertiary structure

hydrophobic affect between non-polar R-Groups

Van der Waals interactions

weak attractions between atoms close to each other

quartenary structure

interactions of R-groups of two or more polypeptides

how does a protein become denatured

high head

low pH

what are polymers of nucleotides

nucleic acids (DNA and RNA)

what does DNA include?

nucleotides, strand, double helix, chromosome, genome

what are nucelotides held by

covalent bonds

what are strands held together by

phosphodiester bonds

what is a double helix held together by?

hydrogen bonds

what is a hairpin

sections of the RNA sequence that are complementary to each other

gene expression

explain how a gene becomes a protein

genes are turned off whenever/wherever

include transcription and translation

central dogma

DNA -> RNA -> Protein

gene sequence of DNA that makes instructions to make a protein

transcription

DNA --> mRNA

(make a copy)

translation

mRNA --> protein

(new language)

where does translation and transcription happen in prokaryotic cells?

cytoplasm

where does translation and transcription happen in eukaryotic cells?

transcription happens in the nucleus, translation happens in the cytoplasm

what are the 2 exceptions to the central dogma?

when a functional RNA is synthesized

retroviruses- RNA viruses (HIV)

how does reverse transcription work?

uses RNA transcriptase to reverse-transcribe RNA genomes into DNA, which is then integrated into the host genome and replicated along with it.

what is a gene?

segment (sequence) of DNA that encodes for one protein

example: chromosomes cookbook, genes recipes

what is the coding strand?

strand of DNA that is complementary to the template strand

(non-template)

Carries information to make proteins

what is the non-coding strand?

template strand

promoter

sequence in gene that marks the location on the template strand

starts transcription

What is the "+1" site of a gene?

first nucleotide that is transcribed

direction of transcription

upstream

lies towards the 5' end of the DNA coding strand, 5' side

downstream

is in the direction of transcription, moving toward the 3' side

Consider a fragment of DNA that has a total of 10 base pairs. Four of these contain Adenine and six contain Guanine. How many hydrogen bonds would there be in this fragment between purine/pyrimidine pairs?

2*4 =8

3*6 =18

18+8=26

26 hydrogen bonds

If adenine makes up 20% of the bases in a DNA double helix, what percent of the bases are guanine?

30%

You isolate a nucleic acid from a cell. How can you determine whether you have isolated RNA or DNA?

Look at the nitrogenous bases of the molecule (thymine or uracil)

Look at the sugars of the molecule (DNA will have deoxyribose, RNA will have ribose)

transcription

the process in which a particular segment of DNA is converted into RNA

(Creating rna from the dna)

translation

the process of using the information in the RNA to synthesize polypeptides

Translation begins when mRNA becomes associated with a

ribosome

What is the purpose of the genetic code?

It specifies the relationship between a sequence of nucleotides and a sequence of amino acids

What amino acid is specified by the start codon?

Methionine

What structural features are common to all tRNAs?

Cloverleaf pattern with three stem-loops

Acceptor stem for amino acid attachment

initiation of transcription

RNA polymerase binds to promoter

elongation of transcription

RNA polymerase unzips the DNA and assembles RNA nucleotides using one strand of DNA as a template.

termination of transcription

RNA polymerase reaches a terminator sequence (Stop codon) and detaches from the template

initiation of translation

mRNA is attached to a subunit of the ribosome, the first codon is always AUG

elongation of translation

Peptide bonds are formed between amino acids to synthesize a polypeptide.

termination of translation

occurs when a stop codon in the mRNA reaches the A site of the ribosome

what are the three steps in RNA processing?

1. Capping (Addition of 5' cap)

2.Tailing (addition of poly-A tail (3') string of AAAA's)

3. Splicing (removal of introns)

what is the function of capping?

1. helps mRNA exit the nucleus

2. prevents loss of sequence in 5' end (degradation)

3. (in eukaryotes)= help mRNA bind to ribosome

what is the function of a poly-a tail?

prevents degradation (loss of sequence)

Why do we need mRNA in eukaryotic cells?

1. Remove non-coding information

2. Prevents mRNA from loosing sequence

what is a codon?

a three nucleotide sequence in mRNA (64 codons total)

61 codons specify for an _

amino acid

1 Specifies for a __ codon

and the amino acid ___

"start" (known as AUG)

Methionine (Met)

AUG -> MET

3 codons mean __

stop