Chapter 10 Molecular Biology of the Gene

Protein

A functional biological molecule consisting of one or more polypeptides folded into a specific three-dimensional structure.

DNA polymerase

A large molecular complex that assembles DNA nucleotides into polynucleotides using a preexisting strand of DNA as a template.

RNA polymerase

A large molecular complex that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template.

triplet code

A set of three-nucleotide-long words that specify the amino acids for polypeptide chains.

terminator

A special sequence of nucleotides in DNA that marks the end of a gene. In the 3rd phase of transcription,It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene

codon

A three-nucleotide sequence in mRNA that specifies a particular amino acid or polypeptide termination signal; the basic unit of the genetic code.

ribonucleic acid (RNA)

A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses.

Transfer RNA (tRNA)

A type of ribonucleic acid that functions as an interpreter in translation. Each one has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA.

DNA ligase

An enzyme, essential for DNA replication, that catalyzes the covalent bonding of adjacent DNA strands; used in genetic engineering to paste a specific piece of DNA containing a gene of interest into a bacterial plasmid or other vector.

intron

An internal, noncoding region of a gene that does not become part of the final messenger RNA molecule and is therefore not expressed.

amino acid

An organic molecule containing a carboxyl group and an amino group; serves as the monomer of proteins.

DNA (deoxyribonucleic acid)

Capable of duplication, ____ is an oragnism's genetic material with instructions for the cell .

nucleotides

DNA is a polymer made from monomers called ______

any permanent change in the nucleotide sequence of DNA

Define Mutation

DNA is copied complementary to RNA. First, the triplet code converts the nucleotide sequence into an amino acid sequence. The transcription occurs and copies the DNA nucleotide triplet code to RNA nucleotide as codons. The mRNA has a specific codon for a specific amino acid. During translation, the tRNA which has an anticodon for each amino acid picks up a specific amino acid, and conveys the amino acid to the appropriate codon on the mRNA

Define genetic code in biological terms including terms Amino acids, codons, and anticodons

Per Watson an Crick Dna replication follows a semiconservative model- the two strands separate, each strand is used as a pattern to produce a complementary strand using specific base pairing, each new DNA helix has one old strand with one new strand ensuring the somatic cells carry to the same genetic information Begins at the origins of replication (can be at multiple sites), DNA unwinds to produce bubble, proceeds in both directions and from the origin, ends when products from the bubbles merge with each other. Involves 2 key proteins- DNA polymerease ( adds nucleotides to a growing chain, proofreads and corrects improper base pairings.) and DNA ligase (joins small fragments of DNA into a continous chain)

Describe how DNA is replicated

Eukaryotic mRNA has introns (interrupting sequences) that separate and exons (the coding region) mRNA goes the RNA splicing which removes introns and joins exons to produce a continuous coding sequence. Then a cap and tail of extra nucleotide are added to the ends of mRNA to 1. facilitate the export from the nucleus 2. protect it from attack by cellular enzymes 3. Help ribosomes bind to mRNA

Describe how mRNA is processed prior to leaving the nucleus

the flow of genetic information from DNA to RNA to protein

Describe the central dogma of molecular biology

61 codons correspond to amino acids AUG codes for amino acid methimine which always signals start of a protein 3 stops codons sign the end of a protein- UUA, UGA, UAG

Describe the characteristics of the genetic code

tRNA- functions as the interpreter in translation, Each one has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA Has a distinctive folded structure with 3 hairpin loops that form the shape of a 3 leafed clover. One of these hairpin loops contain a sequence called the anticodon, which can receive and decode an mRNA codon. Each tRNA has a corresponding amino acid attached to its end.

Describe the general structure/characteristic of tRNA

mRNA- encodes genetic information form DNA and conveys it to ribosomes, where the information is translated into amino acid sequences a short-single stranded molecule contain A, C, G, U exons 5' and 3' poly tail (because RNA splicing removes introns and joins the exons to produce continuous coding sequence) codon-made in the nucleus during transcriptions when DNA is made into RNA, it is used to carry the genetic code from DNA to the ribosomes, translation coverts this into a protein

Describe the general structure/characteristics of mRNA

rRNA- type of DNA that together with proteins make up ribosomes; the most abundant type of RNA in most cells ribosome are about 60% RNA and 40% protein made in the nucleolus in the nucleus and then transported to the cytoplasm via nuclear pores 2 subunits- large ribosomal sub-unit and small ribsomal sub-unit It moves along on mRNA molecule, catalyze the assembly of amino acids into protein chains, also bind tRNA and various accessory molecules necessary for protein synthesis

Describe the general structure/characteristics of rRNA

1. Begins with initiation, as the RNA polymerase attaches to the promoter 2. During the 2nd phase, elongation- the RNA grows longer , as the RNA peels away the DNA strands rejoin 3. Final phase, termination- the RNA polymerase reaches a sequence of bases in the DNA template called a terminator, which signals the end of the gene. The polymerase molecule now dettaches from the RNA molecule and the gene.

Describe the phases of transcription

A gene is the poly nucleotide sequence with information to make one polypeptide. Each codon- a triplet of bases in DNA or RNA-codes for one amino acid. Transcription occurs when RNA polymerase produces RNA one strand of DNA as a template. In prokaryotic cells, the RNA transcription immediately serve as MRNA. In eukaryotic cells, the RNA is processed; a cap and tail are added, and RNA splicing removes introns and links exons together to form a continuous coding sequence. A ribosome is the site of translation, or polypeptide synthesis, and tRNA molecules serves as interpreters of the genetic code. Each folded tRNA molecule has an amino acid attached at one end and a 3 base anticodon at the other. Beginning at the start codon, adding its amino acid to the polypeptide chain. The amino acids are linked by peptide bonds. Translations stops at a stop codon, and the finished polypeptide is release. The polypeptide folds to form a functional protein, sometimes in combination with other polypeptides.

Describe the process by which the information in a eukaryotic gene is transcripted and translated into a protein

Ingredients: original DNA, nucleotides, several enzymes and other proteins-including DNA polymerase and DNA ligase. Steps: original DNA strands separate at a specific site (origin of replications), free nucleotides hydrogen-bond to each strand according to base pairing rules, and DNA polymerease covalently bonds the nucleotides to form new strands. New nucleotides are added only to the 3' ends of a growing strand. One new strand is made in one continuous place; the other new strand is made in a series of short pieces that are then joined by DNA ligase. Products: two identical DNA molecules, each with 1 old strand and 1 new strand

Describe the process of DNA replication, the ingredients needed, the steps in the process, and the final products

Occurs in the nucleus the synthesis of RNA on a DNA template 1. begins with initaiton as the RNA polymerase (the transcription enzyme) attaches to the promoter (the start-transcribing signal) 2. the second phase, elongation, the RNA grows longer as he RNA Peels away, the DNA strand rejoin 3. The thrid phase termination, the RNA polmerase reaches a sequence of bases in the DNA Template called a terminator, which signals the end of the gene. The polymerase molecule deattaches from the RNa Molecule and the gene Creates a strand of mRNA

Describe the process of transcription and where it occurs

Occurs in the cytoplasm of the surface of the ribosome the synthesis of a polypeptide using genetic information encoded in an mRNA molecule. There is a change in language from nucleotide to amino acid. The synthesis of proteins under RNA Brings amino acid to ribosomes then transfer, its amino acid to the growing chain of amino acids during protein synthesis 1. Initiation brings mRNA, tRNA (bearing the 1st Amino acid), rRNA (two subunits of ribosome) together- mRna binds to small subunit at the start codon tRNA with anticodon bind to the P site with the 1st AA, the large subunit binds to the small subunit to form the a functional ribosome 2. Elongation and termination- the mRNA moves one codon at a time along the ribosome and a tNRA with a complementary anticodon pairs with each codon adding its amino acid to the growing polypeptide chain. Elongation continues until a stop codon reaches the ribosomes A site and the entire complex separates

Describe the process of translation and where it occurs

genetic code

Determines which triplet code and codon determines which amino acid, that there are 61 codons, AUG is always the start of a protein and codes for methionine, UUA, UGA, UAG will always stop the protein.

DNA- dexoribose sugar covalently bonded to a phosphate gorup and nucleotide base A, T, G, C. Double stranded RNA-ribose sugar covalently bonded to a phosphate group and nucleotide base A, U, G, C. Single stranded

Difference between DNA and RNA

Melanoma- a simple base change from an A to T in the BRAF at the 1796th base causes melanocytes to keep moving through the cell cycle rapidly Sickle cell anemia- mutant hemoglobin DNA, inherited, causes cells to be hard, sticky, and shaped like sickles- cause clogs in small blood tubes and the pointed edges break it apart causing pain, low blood count, or anemia

Examples of Base substitutions mutations

DNA (deoxyribonucleic acid)

Has deoxyribose sugar covanlently bonded to the phosphate group creating a sugar phosphate backbone also attached to the nucleotide base (A,T, C, G)

Showed that in DNA, the amount of Adenine was equal to thymine, and the amount of guanine was equal to that of cytosine

How did Edwin Chargaff contribute to DNA

examined DNA fivers, noticed the pattern generated looked like a coil of some type, conclude that DNA was a helix of some sort

How did Rosalind Franklin contribute to DNA

stated that DNA replication follows a semi conservative module reported that DNA consisted of 2 polynucleotide strands wrapped into a double helix- sugar phosphates backbone on the outside, nitrogenous bases perpendicular to the backbone in the interior, specificied pairs of bases give the helix its uniform shape A-T with 2 hydrogen bonds G-C with 3 hydrogen bonds

How did Watson and Crick contribute to DNA

Silent mutation-codes for the same amino acid in the protein and has not effect at all Missense mutation- codes for a different amino acid in the protein; can have no effect or can cause an issue with the proteins Nonsense mutation- change an amino acid into a stop codon producing a non-functional protein Can cause cancer

How does Base substitutions effect protein systhesis

May alter the reading frame (triplet grouping) of the mRNA, so that nucleotides are grouped into different codons Lead to significant chagnes in Amino Acid sequence downstream of mutation Produce nonfucntional protein

How does frameshift mutations effect protein synthesis

1. Spontaneous errors that occur during DNA replication or recombination 2. Mutagens- high energy radiation (xrays and UV light that link adjacent T's together in a single strand of DNA or cause both strands to break. Can be chemicals like those found in cigratte smoke 3. Collision of water molecules with DNA can remove nucleotide bases 4. Digesting food and produce by products that are called free radicals that can damage DNA

Identify causes of mutations

anticodon

On a tRNA molecule, a specific sequence of three nucleotides that is complementary to a codon triplet on mRNA.

introns; exons

RNA splicing removes ____ and joins ____ to produce a continuous coding sequence.

Ribosomal RNA (rRNA)

Ribosomes are composed of 2 subunits of ________ that are made in the nucleolus in the nucleus and then transported to the cytoplasm via the nuclear pores. Large and small subunits united in the cytoplasm to become ribosomes

mRNA: GAU, GCG, AUC Amino Acid: Met Arg Ser

The base sequence of the gene coding for a short polypeptide is CTA CGC TAG What would be the base sequence of the mRNA transcribed from this gene? Using the genetic cod, give the amino acid sequence fo the polypeptide translated from this mRNA.

GUA

The nucleotide sequence of a DNA codon is GTA. A messenger RNA molecule with a complementary codon is transcribed from DNA. In the process of protein synthesis, a transfer RNA pairs with the mRNA codon. What is the nucleotide sequence of the tRNA anticodon?

DNA, transcription, RNA, translation, protein

The order of how DNA becomes Protein

exon

The part of a gene that becomes part of the final messenger RNA and is therefore expressed.

RNA splicing

The removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence; occurs before mRNA leaves the nucleus.

genetic code

The set of rules that dictates the amino acid translations of each mRNA nucleotide triplet.

Translation

The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of language from nucleotides to amino acids.

translation

The synthesis of a protein (polypeptide). Takes place on ribosomes, using the information encoded in messenger RNA, brings amino acid to ribosomes then transfer its amino acid to the growing chain of amino acids during protein syntheses, has specific amino acid attach to one end and 3 nucleotide called anticodon to the other end

Messanger RNA (mRNA)

The type of ribonucleic acid that encodes genetic information from DNA and conveys it to ribosomes, where the information is translated into amino acid sequences.

Ribosomal RNA (rRNA)

The type of ribonucleic acid that, together with proteins, makes up ribosomes; the most abundant type of RNA in most cells.

1. Base substitutions 2. Frameshift mutations

Types of mutations

UUA, UGA, UAG

What are the stop codons?

2 DNA strands separate, each strand is used as a pattern to produce a complementary strand, using specific base pairing, each new DNA helix has one old strand with one new strand

What happens in the semi-conservative replication model

AUG

What is the start codon?

RNA

Which can leave the nucleus: DNA or RNA

tRNA

Which of the following attaches the amino acids into a chain: tRNA or mRNA

Translation

Which of the following converts mRNA into a protein: translation or transcription

DNA polymerase

_____ involved in DNA replication because it adds nucleotide to a growing chain and it also proofreads and corrects improper base pairings

Transcription

______ copies the DNA nucleotide triplet code to RNA nucleotides as codons

translation

______ switches from the codon nucleotide "language" to the amino acid "language"

polypeptide

a bunch of amino acids attached together is called a _____

mutation

a change in the genetic information of a cell; the ultimate source of genetic diversity. It can also occur in the DNA or RNA of a virus.

DNA (deoxyribonucleic acid)

a double-stranded, helical nucleic acid molecule, consisting of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G) and thymine (T); capable of being replicated and determining the inherited structure of a cell's proteins

subsitution

a geneticist found that a particular mutation had no effect on the polypeptide encoded by a gene. This mutation probably involved _______

tail

a long chain of adenine nucleotides that is added to a mRNA molecule during RNA processing to increase the stablity of the molecule

cap

a modified base (guanine nucleotide) attached to the 5' end of eukaryotic mRNA molecules; it protects the transcript from being broken down, also helps the ribosome attach to the mRNA, and starts reading it to make a protein.

ribonucleic acid (RNA)

an intermediary directs the cells to make proteins; has ribose sugar bonded to either G, A, C, U

mutation

any permanent change in the nucleotide of DNA; can involve large chromosomal regions or just a single nucleotide pair; some are not harmful to the cell or the organism overall and some have deadly effects

mRNA

encodes genetic information from DNA and conveys it to ribosomes, where the information is translated into amino acid sequences

tRNA

functions as the interpreter in translation. Each on has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA

transcription

is the name of the process that produces RNA from a DNA template

translation

is the name of the process that produces a polypeptide from an RNA template

DNA ligase

joins smalls fragments of DNA into a continuous chain

transcription

mRNA is made during which of the following transcription or translation

nucleus

mRNA is made in which of the following cytoplasm or nucleus

ribosomes

proteins are made at which of the following: nucleus or ribosomes

amino acid

proteins made from one or more polymers made from monomers called _____

protein synthesis

requires the conversion of the nucleotide sequence to an amino acid sequence

mRNA, rRNA, tRNA

ribosomes use amino acid bearing molecules called _______

Semi-conservative replication model

states that the type of DNA replication in which the replicated double helix consist of one old strand, derived from the old molecule and one from the newly made strand

Transcription

synthesis of an RNA molecule from a DNA template or direction of DNA

cytoplasm

tRNA is found in the which of the following: nucleus or cytoplasm

translation

tRNA is used in which of the following: translation or transcription

anticodons

tRNA uses which of the follow to match to the mRNA: anticodons or codons

translation

the 2nd step of protein synthesis

anticodon

the bases on tRNA are called ____

codon

the bases on the mRNA strand are called ____

amino acid

the building blockes to make a wide variety of proteins; there are 20 different types; the order in which they are bound in a protein, will dictate the fx of the protein

transcription

the first step of protein synthesis

triplet code

the set of rules that dictates the amino acid translations of each mRNA nucleotide triplet, the sequence of nucleotide in DNA provides this for the sequence of amino acids in a protein- every 3 nucleotides code for 1 specific amino acid, or protein synthesis requires the conversion of the nucleotide sequence to an amino sequence

Promoter

the start transcribing signal; a nucleotide sequence transcription begins with initiation as the RNA polymerase attaches to this

rRNA

together with proteins make up ribosomes; the most abundant type of RNA in most cells.

RNA polymerase

transcription is performed by an enzyme called ______

nucleus

transcription take place in which of the following nucleus or cytoplasm

ribosomes

translation is performed by structures called ______

Cytoplasm

translation take place in which of the following: cytoplasm or nucleus

cap and tail

two things that:Facilitates the export of the mRNA from the nucleus, protects the mRNA from attack by cellular enzymes, and helps ribosomes bind to the mRNA

base substitution mutation

type of mutation that involve the replacement on one nucleotide with another

frameshift mutation

type of mutation that result from deletions or insertions

1. DNA unwinds here to produce a bubble 2. Replication proceeds in both directions from the origin 3. Replication ends when products from the bubbles merge with each other

what happens at the origin of replication

origin of replication

where DNA replication begins

nucleus

where does the 1st step of protein synthesis occur

cytoplasm

where does the 2nd step of protein synthesis occur

amino

which of the following acids make up a protein: RNA or amino

Transcription

which of the following coverts DNA into mRNA: translation or transcription

mRNA

which of the following is used to carry the genetic code from DNA to the ribosomes: mRNA or rRNA

rRNA

which of the following makes up the ribosomes: tRNA or rRNA