bio midsem flashcards

That in DNA, percentages of A and T are the same, and G and C are the same.

The process by which DNA directs the synthesis of proteins. The expression of genes that code for protein includes 2 stages: transcription and translation.

• normally found in sandy deserts, partly covered in black lava
• camouflage provides protection from predation
• colour of species that doesn't camouflage becomes less common
• selection pressures e.g. predators, environment

• can isolate DNA from mammoths and compare it to the gene that caused mouse fur to change colour
• found that some mammoths had the light fur gene and some had the dark fur gene

• Genetic make-up of an organism --> 'blueprint'
• genetic information

• detectable properties or traits of an organism
• physical expression of the genotype

phenotypic differences which natural selection can act upon

A large polymer, made up of many monomers.

• A nucleotide.
• Components: sugar, a phosphate and a base

• Adenine, thyamine, Guanine and Cytosine
• The order in which they are arranged is how they information is stored.

• organisms are selected based on their interaction with the environment
• some of their success is due to genetic variation (inherited traits)
• genotypic differences lead to phenotypic differences which natural selection can act upon

Covalent bonds. (strong bonds formed when electrons are shared between two atoms.)

A polymer (chain) of man amino acids linked together by peptide bonds.

The covalent bond between the carboxyl group on one amino acid and the amino group on the next, formed by a dehydration reaction.

Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

• Purines: Adenine and Guanine
• Pyramidines: Cytosine, Thyamine and Uracil

Deoxyribose in DNA and Ribose in RNA

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. organisms with eukaryotic cells (protists, plants, fungi and animals) are called eukaryotes.

A polymer consisting of many nucleotide monomers in a chain; nucleotides can be those of DNA or RNA

a polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The two types are DNA and RNA.

A nitrogenous base (A T G C), a five-carbon sugar (pentose) and a phosphate group.

the portion of the unit nucleotide, without the phosphate group.

• six-membered ring of carbon and nitrogen atoms
• Cytosine, thyamine and uracil
• smaller than purines

• six membered ring fused to a five membered ring
• larger than pyrimidines
• adenine and guanine

• DNA
• RNA

• ribose
• deoxyribose

• phosphodiester bonds
• consists of a phosphate group that links the sugars of two nucleotides
• this bonding results in a backbone with a repeating pattern of sugar-phosphate units.

one end has a phosphate attached to a 5' carbon, and the other end has a hydroxyl group on a 3' carbon

protein's three-dimensional structure and function in the cell.

• opposite directions from each other
• 5' --> 3'
• 'antiparallel' like a divided highway

polynucleotides

• hydrogen bonds between the paired bases
• vanderwaals forces between the stacked bases

thyamine

cytosine

the fact that the two strands of the double helix are complementary

the comparison of a polypeptide chain of human hemoglobin with the corresponding hemoglobin polypeptide in five other vertebrates. In this chain of 146 amino acids, humans and gorillas differ in just 1 amino acid, while humans and frogs differ in 67 amino acids

the phage DNA entered bacterial cells, but phage proteins did not. They concluded that DNA, not protein, functions as the genetic material of phage T2.

• Because the diameter of the double helix allows for only purines to be paired with pyrimidines
• if pyrimidines are paired with pyrimidines, the diameter is too narrow, and vice versaw with purines
• also, adenine can form two hydrogen bonds with thyamine and only thiamine
• guanine forms three hydrogen bonds with cytosine and only cytosine.

the order of nitrogenous bases and amino acids

change to the biological information. i.e. changes to the sequences of monomers in a polymer

• are weak bonds
• occur between an electronegative atom (usually nitrogen, oxygen or fluorine) and hydrogen

• 5 prime
• has a phosphate group attached to it

• 3 prime
• has a hydroxyl group attached to it

Proteins

genes.

Alternative versions of genes that produce different phenotypes

• bacteria - help defend body against bacteria/viruses
• muscle proteins actin and mysoin enable muscle movement
• hemoglobin in the blood - oxygen carrier

• The synthesis of RNA under the direction of DNA
• information is transcribed/copied from one molecule to the other

A type of RNA molecule that carries a genetic message from the DNA to the protein-synthesizing machinery of the cell

• Translation is the synthesis of a polypeptide, which occurs under the direction of mRNA
• During this stage, there is a change in language: the cell must translate the base sequence of an mRNA molecule into the amino acid sequence of a polypeptide.
• The sites of translation are ribosomes

• Site of translation
• complex particles that facilitate the orderly linking of amino acids into polypeptide chains

• Because bacteria do not have nuclei, their DNA is not segregated from ribosomes.
• In a eukaryotic cell, the nuclear envelope separates transcription from translation in space and time.

• A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
• written in the 5' to 3' direction

it stand for the amino acid methionine and is a 'start' signal for ribosomes to begin translating the mRNA at that point

• 3:
• UAA
• UGA
• UAG

• The one of the two DNA strands that is transcribed for each gene.
• It is called the template strand because it provides the pattern, or template for the sequence of nucleotides in an RNA transcript

An enzyme that links ribonucleotides into a growing RNA chain during transcription.

A change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. Mutations also can occur in the DNA or RNA of a virus.

DNA to RNA to Protein

• which dna strand will be the template strand
• where transcription starts
• serves as a binding site for rna polymerase

the stretch of DNA that is transcribed into an RNA molecule

the end of protein synthesis triggered by a stop codon which binds release factor that causes the polypeptide to release from the ribosome

a change in gene sequence that, due to the redundancy of the genetic code, has no effect on the amino acid produced, and thus no effect on the phenotype.

• both assemble nucleic acid chains from monomer nucleotides whose order is determined by complementary base pairing to a template strand
• both synthesize in the 5' to 3' direction, antiparallel to the template
• dna polymerase requires a primer but RNA polymerase can start a nucleotide chain from scratch
• dna polymerase uses nucleotides with the sugar deoxyribose and the base T, whereas RNA polymerase uses nucleotides with the sugar ribose and the base U

The promoter is the region of DNA to which RNA polymerase binds to begin transcription, and it is at the upstream end of the gene.

• In a bacterial cell, RNA polymerase recognizes the gene's promoter and binds to it.
• in a eukaryotic cell, transcription factors mediate the binding of RNA polymerase to the promoter

an enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template

a short stretch of RNA with a free 3' end, bound by complementary base pairing to the emplate strand that is elongated with dna nucleotides during rna replication

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA

A population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not viable, fertile offspring with other such groups.

DNA polymerase III and DNA polymerase I

• degenerate but unambiguous
• universal
• non overlapping
• start and stop codons

an adaptor molecule called tRNA

• Amino acid is attached to the corresponding tRNA by aminoacyl tRNA synthetase
• Codon/anticodon interaction

charged, or activated

ribosome

rRNA and proteins

• Using information from a template mRNA
• Amino acids are linked by covalent bonds
• Protein grows in one direction only
• Amino acids added to C terminus
• Energy requiring

• The A (amino acyl) site -The next amino acid/tRNA waits for peptide bond formation
• The P (peptidyl) site -Holds the growing protein attached to a tRNA

• Initiation
• elongation
• termination

after RNA polymerase binds to the promoter, the DNA strands unwind, and the polymerase initiates RNA synthesis at the start point on the template strand

the polymerase moves downstream, unwinding the DNA and elongating the RNA transcript 5' to 3'. in the wake of transcription, the DNA strands re-form a double helix.

Eventually the RNA transcript is released and the polymerase detaches from the DNA.

• Identification of the AUG start codon
• Insertion of the first charged tRNA, the initiator tRNA
• Assembly of the ribosome
• The small ribosomal subunit interacts with mRNA, and the initiator tRNA
• When the large subunit attaches, the Met-tRNA is in the P site

• A three step cycle:
• Entry of tRNA into the A site
• Formation of peptide bond by peptidyl transferase
• Translocation (movement of the ribosome by one codon)
• The mRNA is translated 5' to 3'

• amplification.
• one gene, many mRNAs, more proteins

• no nucleus,
• transcription and translation in the same compartment

• transcription in nucleus
• translation in cytoplasm

• A heritable change in DNA sequence
• mutations occur at random

• exposure to radiation or chemicals, e.g. uv light and x rays, cigarette smoke burnt meat
• a result of DNA replication errors, ie replication not 100 per cent accurate

yes, no.

the base change does not result in a protein change

a single amino acid is changed

• an amino acid codon is changed to a stop codon
• up to one third of genetic diseases are caused by nonsense mutations
• some drugs cause the ribosome to read through the stop codon

shape of blood cell, disc or sickle shape

• nucleotides are inserted or deleted, resulting in the loss of the normal reading frame
• insertion/deletion is not a multiple of 3

• Mutations in genes cause enzymes to become dysfunctional, leading to disease (sickle cell anaemia)
• Mutations in genes sometimes improve function, (Belgian blue cattle and mighty mouse)
• Mutations can occur in non-coding DNA and have phenotypic effects by altering regulation of genes eg promoter mutations
• Mutations may have little or no effect on phenotype
• Mutations are the raw material for evolution

• The roles of DNA, RNA and protein in he expression of genetic information
• Transcription (RNA synthesis)
• Translation (protein synthesis)
• The genetic code
• Mutations and their phenotypic effects

made only when needed

made all the time

• transcription (most common)
• translation
• protein activity

lactase

• Regulation is important in development and in responding to environmental change
• Genes are controlled by genetic switches that turn them on and off.

A mechanism by which the rate of transcription can be altered

A mechanism for sensing the environment

describing the mRNA that encodes for multiple different polypeptides