Chapter 4.5 Flashcards
What is held in DNA?
The information that instructs a cell to synthesize a particular protein
What constitutes the genetic code?
The correspondence between a unit of DNA information and a particular amino acid
What is a gene?
A DNA sequence that contains the information for making a particular polypeptide
What is a genome?
The complete set of genetic instructions in a cell, including the genes as well as other DNA sequences
human genome consists of how many dna nucleotides?
3.2 billion
What is a exome?
A small part of the human genome that encodes proteins
What is gene expression?
When proteins are produced in a particular cell under particular circumstances and the amounts produced
What does a nucleotide consist of?
a 5-carbon sugar(ribose or deoxyribose), a phosphate group, and one of several nitrogenous bases
What is a DNA molecule?
A double-stranded molecule, consisting of two polynucleotide chains. Nitrogenous bases project from the sugar-phosphate backone of one strand and bind by hydrogen bonding to the nitrogenous bases of the second strand
What are the four types in DNA?
Adenine, Thymne, Cytosine, or Guanine
What are the purines?
A and G, and consist of two organic ring structures?
What are Pyrimidines?
T and C, and they have a single organic ring structure.
What does A bind to?
T
What does G bind to?
C
What are the complementary base pairs?
A-T, and G-C
What are histones?
In the nucleus, DNa is wound around proteins called this, clustered in groups of eight to form chromatin
What is DNA Replication?
The process that creates an exact copy of a DNA molecule. It happens during interphase of the cell cycle
As DNA replication begins,
hydrogen bonds break down the complementary base pairs of the two strands
What does DNA polymerase do?
Catalyzes this base pairing
During mitosis, the two DNA molecules
that form the two chromatids of each of the chromosomes separate so that one of these DNA molecules passes to each of the new cells
Genetic information specifies
the correct sequence of amino acids in a polypeptide chain.
How many amino acids are in the body?
Twenty
Each of the 20 amino acids represented by
a triplet code, consisting of sequences of three nucleotides
What is transcription?
The process of copying DNA information into an RNA sequence
RNA nucleotides have
ribose rather than deoxyribose sugar
Like DNA, RNA nucleotides
each have one of four nitrogenous bases, but whereas thymine is only in DNA. Instead, RNA has Uracil.
Main location of DNA?
Part of chromosomes, in nucleus
Main location of RNA??
Cytoplasm
DNA - 5 Carbon Sugar
Deoxyribose
RNA - 5 Carbon Sugar
RIbose
DNA - Basic molecular structure
double-stranded
RNA - Basic molecular structure
singe-stranded
DNA - Nitrogenous bases included
C, G, A, T
RNA - Nitrogenous bases included
C, G, A , U
DNA Major Functions
Contains genetic code for protein synthesis, replicates prior to mitosis
RNA Major Functions
Messenger RNA carries transcribed DNa information to cytoplasm and acts as template for synthesis of protein molecules, transfer RNA carries amino acids to messenger RNA, ribosomal RNA provides structure for ribosomes
First step in transcription?
The synthesis of messenger rna. RNA carries a genes information on how to build a specific polypeptide.
In mRNA synthesis,
RNA polymerase binds to a promoter, which is a DNA base sequence that begins a gene
RNA polymerase moves
along the strand, exposing other sections of the gene.
At the same time, a molecule of mRNA forms as
RNA nucleotides complementary to those along the DNA strand are joined
RNA polymerase continues to move along
the DNA strand, exposing successive sections of the base sequence, until it reachs a special DNA base sequence that indicates the end of the gene
What are codons?
A series of three bases in mRNA
To carry out protein synthesis,
mRNA must leave the nucleus and associate with a ribosome.
What is translation?
There, the mRNA is translated form the “language” of nucleic acids to the “language” of amino acids in a process
What are Exons?
Most genes are transcribed in “pieces”
What are Introns?
Sectiosn are spliced out of messenger RNA molecules before the molecules are used to synthesize proteins
Synthesizing a protein molecule requires that
the specified amino acid building blocks in the cytoplasm align in the proper sequence along an mRNA and then attach.
What is Transfer RNA?
Aligns amino acids in a way that enables enzymes to bond them to each other,
How many different mRNA codons can be made?
64
How many mRNA codons do not hae corresponding tRNA?
Three
What is the mRNA sequence that is the initiation code?
AUG
What is a ribosomal rna?
A ribosome is an organelle that is a tiny particle of two unequal-sized subunits composed of rRNA molecules and protein molecules
What are chaperones?
As a polypeptide forms, this folds it into its unique shape, and when the process is completed, the polypeptide is released as a separate functional molecule
Where does Transcription occur?
In the Nucleus
Where does Translation occur?
In the cytoplasm
First step in Transcription?
RNA polymerase binds to the DNA base sequence of a gene
Second step in Transcription?
This enzyme unwinds and exposes part of the DNA molecule?
Third step in Transcription?
RNA polymerase moves along one strand of the exposed gene and catalyzes synthesis of an mRNA, whose nucleotides are complementary to those of the strand of the gene
Fourth Step in Transcription?
When RNA polymerase reaches the end of the gene, the newly formed mRNA is released
Fifth step in TRanscription?
DNA rewinds and closes the double helix
Sixth step in Transcription?
The mRNA passes through a pore in the nuclear envelope and enters the cytoplasm
First step in TRanslation?
a ribosome binds to the mRNA near the codon at the beginning of the messenger strand
Second step in translation?
a tRNA molecule that has the complementary anticodon brings its amino acid to the ribosome
third step in translation?
a second tRNA brings the next amino acid to the ribosome
fourth step in translation?
a peptide bond forms between the two amino acids, and the first tRNA is release
fifth step in translation?
the process repeats for each codon in the mRNA sequenceas the ribosome moves along its length, forming a chain of amino acids
sisth step in translation?
the growing amino acid chain folds into the unique conformation of a functional protein
seventh step in translation?
the completed protein molecule is released. the mRNA, ribosome, and tRNA are recycled
