Notes set 3 Molecular Biology and Evolution Review

Flashcards covering molecular mutations, genetic transcription and translation, cellular metabolism, and the principles and evidence of evolution.

Mutation

Any permanent change in an organism's DNA, acting as a modification in the cell's information archive.

Point mutation

A result of a single base change in the DNA sequence.

Missense mutation

A replacement mutation that results in changes in the amino acid sequence of the encoded protein.

Silent mutation

A mutation that does not change the amino acid sequence of the gene product; usually neutral in effect.

Beneficial mutation

A mutation that increases the fitness of the organism.

Neutral mutation

A mutation that does not affect an organism's fitness.

Deleterious mutation

A mutation that decreases the fitness of the organism.

Polyploidy

A chromosome-level mutation involving an increase in the number of each type of chromosome.

Aneuploidy

A chromosome-level mutation involving the addition or deletion of a single chromosome from the individual's karyotype.

Inversion

Occurs when sections of a chromosome break and rotate before rejoining the chromosome.

Translocation

Occurs when a broken section of one chromosome becomes attached to another chromosome.

Transcription

The first step in converting genetic information into proteins, involving the synthesis of an mRNA version of instructions stored in DNA.

Template strand

The specific strand of DNA that RNA polymerase transcribes during synthesis.

Coding strand

Also known as the non-template strand, it matches the sequence of the mRNA except that RNA has uracil (U) in place of thymine (T).

RNA polymerase

An enzyme that performs template-directed synthesis in the 5' to 3' direction; unlike DNA polymerase, it does not require a primer.

Sigma

A prokaryotic protein subunit that must bind to RNA polymerase to initiate transcription by guiding it to specific promoter sequences.

Holoenzyme

An enzyme made up of a core enzyme and other required proteins, such as the prokaryotic RNA polymerase core enzyme combined with a sigma subunit.

Promoter

DNA sequences that define where the transcription of a gene by RNA polymerase begins.

Basal transcription factors

A group of proteins in eukaryotes that bind to the DNA promoter to initiate transcription.

Hairpin structure

A structure formed by RNA in bacteria that serves as a transcription termination signal, causing RNA polymerase to separate from the transcript.

Exons

The coding regions of eukaryotic genes that will be part of the final mature mRNA product.

Introns

Intervening noncoding sequences in eukaryotic genes that are removed during RNA processing.

Splicing

The process of removing introns from the primary RNA transcript.

snRNPs

Small nuclear ribonucleoproteins that form a complex called a spliceosome to catalyze the splicing reaction.

5' cap

A modified structure added to the 5' end of eukaryotic mRNA that serves as a recognition signal for the translation machinery.

Poly(A) tail

A sequence of adenine nucleotides added to the 3' end of mRNA that protects it from degradation.

Translation

The process where the sequence of bases in mRNA is converted into an amino acid sequence in a protein.

Polyribosome

A structure formed by multiple ribosomes attached to a single mRNA, allowing simultaneous translation.

Transfer RNA (tRNA)

An adapter molecule that holds amino acids in place while interacting with a specific codon in mRNA.

Aminoacyl tRNA synthetase

Enzymes that "charge" tRNA by catalyzing the addition of specific amino acids to them.

Aminoacyl tRNA

A tRNA molecule covalently linked to its corresponding amino acid.

Anticodon

The triplet on the loop of a tRNA molecule that base pairs with the mRNA codon.

Wobble hypothesis

Proposed by Francis Crick, it suggests that the anticodon of a tRNA can bind to a codon whose third position requires a nonstandard base pairing.

Ribosome A site

The acceptor site in the ribosome for an aminoacyl tRNA.

Ribosome P site

The site in the ribosome where a peptide bond forms, adding an amino acid to the growing polypeptide chain.

Ribosome E site

The site in the ribosome where tRNAs no longer bound to amino acids exit.

Molecular chaperones

Proteins that speed up the folding of other proteins, which determines the protein's shape and function.

Anabolism

Metabolic pathways involving the assembly of large molecules, which usually require enzymes and energy in the form of ATP.

Catabolism

Metabolic pathways involving the breakdown of molecules to access energy storage or recycle cell components.

Glycolysis

The first stage of cellular respiration occurring in the cytoplasm, which splits glucose into 2 ATP and 2 pyruvate molecules.

Vertical Gene Transfer

The transfer of genes from parents to offspring.

Horizontal Gene Transfer

The transfer of genes between individuals of the same or different species, frequent in unicellular organisms.

Evolution

Any change in a population's allele frequencies over time.

Biological Species Concept (BSC)

Defines species as groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.

Morphospecies concept

A rule of thumb stating that members of the same species usually look alike.

Ecological Species Concept (ESC)

Suggests a species can be characterized by its ecological niche, representing the role it plays in its environment.

Allopatric speciation

The evolution of separate species from an ancestral population due to a period of geographical separation.

Sympatric speciation

The evolution of separate species from the same ancestral population without geographical separation.

Homologous structures

Structures, such as pentadactyl limbs, that share a common ancestral plan but are modified for different uses or habitats.

Analogous structures

Structures that result from convergent evolution, where different species develop similar traits independently.

Vestigial structures

Structures that have lost their original function through evolution, such as the coccyx or wisdom teeth.

Cytochrome C

An essential protein in energy metabolism used to show variations between species that support the theory of evolution.

Genetic drift

Random changes in allele frequency due to chance events.

Gene flow

Changes in the gene pool of populations resulting from immigration or emigration.

Australopithecus afarensis

An upright primate and vegetarian with sexual dimorphism that lived approximately 4 to 5 million years ago.

Homo habilis

The first tool maker with an enlarged brain, living approximately 2.6 million years ago.

Homo sapiens

The only surviving Homo species, emerging between 100,000 and 200,000 years ago.