BMB 280 Exam 3

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mutation within a gene
one of the nucleotides in the gene is altered, directly affects how the gene is coded, may affect function
mutation in regulatory DNA
mutation in the promoter region. in the 5' untranslated region. changes how the gene is expressed.
gene duplication
copies of the gene are made. give rise to families of related genes. a misalignment in homologous chromosomes result in unequal crossover which leads to a long chromosome
exon shuffling
the exons in the two genes are swapped between genes. can result in new genes. Mechanism for the evolution of new genes. in the process, coding sequences from different genes are brought together to generate a protein with a novel combination of domains.
transposition
transposons (mobile genetic elements) moves from places of DNA with no function into genes with a function.
horizontal transfer
gene from one organism moves to another organism. bacterial mechanism. exchange of genetic information. Process by which DNA is passed from the genome of one organism to that of another, even to an individual from another species. This contrasts with vertical gene transfer of genetic information from parent to progeny.
germ cells
cells whose genes are passed onto offspring. mutations in germ cells are passed from generation to generation. Cell type in a diploid organism that carries only one set of chromosomes and is specialized for sexual reproduction. Sperm/egg/gamete.
somatic cells
mutations are not passed to offspring. any cell that forms part of the body of a plant or animal that is not a germ cell or germ-line precursor.
point mutations
caused by failures of normal mechanisms for copying and repairing DNA. can change the regulation of a gene. affects individual nucleotides in a sequence.
multiple gene duplications and mutations lead too...
new gene function or the loss of gene function
pseudogenes
gene that loses function due to mutations
Tree of life
3 major divisions. bacteria, archea, eukaryotes
mobile genetic elements
transposons/retrotransposons. encode the components needed for movement. contain multiple elements. can move gene elements between genes if excised improperly. Short segment of DNA that can move, sometimes through an RNA intermediate, from one location in a genome to another; an important source of genetic variation in most genomes.
cut + paste transposition
transposon is cut from donor DNA to target DNA
replicative transposition
transposon is replicated onto new DNA sequence
retrotransposons
a type of transposons that employ retroviral-like reverse transcription during the process of transposition. type of mobile genetic element that moves by being first transcribed into an RNA copy that is reconverted to DNA by reverse transcriptase and inserted elsewhere in the chromosome.
retroviruses
reverse the normal flow of genetic information which allows for the assembly of many new infectious virus particles. RNA-containing viruses that replicates into a cell by first making a double-stranded DNA intermediate that becomes integrated into the cells chromosome.
single-nucleotide polymorphins
snps. a single nucleotide change that occurs in populations and accumulates due to reproduction. passed through generation. Form of genetic variation in which one portion of the population differs from another in terms of which nucleotide is found at a particular position in the genome.
Homologous genes
genes that are similar because of their common evolutionary origin.
Gene divergence
Differences in sequence that accumulate over time in DNA segments derived from a common ancestor
Central Dogma
the principle that genetic information flow from DNA to RNA to proteins. structure of DNA provides a mechanism for heredity. DNA to RNA through transcription. RNA to protein through translation.
Chromosomes
Long, threadlike, structures composed of DNA and proteins that carry the genetic information of an organism. Becomes visible as a distinct entity when a plant or animal cell prepares to divide. DNA is highly condensed. contain long strings of genes. each DNA molecule has been packaged into a mitotic chromosome that is 10,000 fold shorter than its fully extended length. interphase chromosomes contain both condensed and extended chromatin.
DNA double helix
the typical structure of a DNA molecule in which the two complementary polynucleotide strands are wound around each other with base pairing between the strands. double, antiparallel strands of DNA. sugar-phosphate backbone. hydrogen-bonded base pairs.
Gene
unit of heredity containing the instructions that dictate the characteristics or phenotype of an organism. in molecular terms a segment of DNA that directs the production of a protein or functional RNA molecule.
Genome
the total genetic information carried by all the chromosomes of a cell or organism.
Replication origin
nucleotide sequence at which DNA replication is initiated. DNA synthesis starts here. two replication forks form at each replication origin. replication forks are asymmetrical.
Telomeres
repetitive nucleotide sequence that caps the ends of linear chromosomes. counteracts the tendency of the chromosome to shorten with each round of replication. end of the chromosome.
Centromeres
specialized DNA sequence that allows duplicated chromosomes to be separated during M phase. can be seen as the constricted region of a mitotic spindle. attachment site to mitotic spindle for segregation.
Nucleolus
large structure within the nucleus where ribosomal RNA is transcribed and ribosomal subunits are assembled. site of rRNA synthesis and ribosome function.
Nucleosome
beadlike structural unit of a eukaryotic chromosome composed of a short length of DNA wrapped around a core of histone proteins. includes a nucleosomal core particle (DNA plus histone protein) along with a segment of linker DNA that ties the core particles together. basic units of eukaryotic chromosome structure. double stranded DNA wrapped around a protein core.
Histones
a group of abundant highly conserved proteins around which DNA wraps to form nucleosomes, structures that represent the most fundamental level of chromatin packing. the protein core that nucleosomes are wrapped around.
Histone tail modification
correlate to chromatin structure. important regulatory sites. methylation=heterochromatin formation, gene silencing. methylation+acetylation=gene expression. phosphorylation+acetylation=gene expression.
DNA replication
the process by which a copy of a DNA molecule is made. enabled by base pairing.
DNA synthesis
the creation of DNA molecules. begins at replication origins. short lengths of DNA act as primers.
DNA polymerase
an enzyme that catalyzes the addition of subunits to a nucleic acid polymer. makes DNA. synthesizes DNA using a parental strand as a template. dNTPS are the DNA polymerase substrate. self correcting by proofreading. contains two active sites. removes RNA primer and replaces it with DNA.
DNA helicase
bind and potential remodel nucleic acids. unwinds the DNA. essential in DNA replication because it separates double stranded DNA into single strands that allow the strands to be copied.
Okazaki fragments
short length of DNA produced on the lagging strand during DNA replication. adjacent fragments are rapidly joined together by DNA ligase to form a continuous DNA strand
DNA ligase
enzyme that seals nicks that arise in the backbone of DNA molecules
Depurination
the removal by hydrolysis of a purine base from DNA
Deamination
the removal of an amino group from a compound
DNA mismatch repair
collective term for the enzymatic processes that correct deleterious changes affecting the continuity or sequence of a DNA molecule
Homologous recombination
mechanism by which double-strand breaks in a DNA molecule can be repaired flawlessly. uses an undamaged, duplicated, or homologous chromosome to guide the repair. during meiosis the mechanism results in an exchange of genetic information between the maternal and paternal homologs.
Transcription
process in which RNA polymerase uses one strand of DNA as a template to synthesize a complementary RNA sequence. produces RNA that is complimentary to one strand of DNA. signals in DNA tell transcription where to start and stop. initiation is a complex process.
Translation
process by which the sequence of nucleotides in a messenger RNA molecule directs the incorporation of amino acids into protein.
RNA polymerase
an enzyme that catalyzes the addition of subunits to a nucleic acid polymer. makes RNA. primase is an example of RNA polymerase. requires general transcription factors.
mRNA (messenger RNA)
RNA molecule that specifies the amino acid sequence of a protein. processed in the nucleus. transported to the cytoplasm through nuclear pores. ribosomes decode message. specific codons signal the ribosome where to start and stop protein synthesis. each mRNA controls its own degradation and translation.
rRNA (ribosomal RNA)
RNA molecule that forms the structural and catalytic core of the ribosome.
tRNA (transfer RNA)
small RNA molecule that serves as an adaptor that reads a codon in mRNA and adds the correct amino acid to the growing polypeptide chain. matches the amino acid to the mRNA codon.
RNA processing
broad term for the modifications that a precursor mRNA undergoes as it matures into an mRNA.
RNA capping
the modification of the 5' end of a maturing RNA transcript by the addition of an atypical nucleotide
Polyadenylation
the addition of multiple adenine nucleotides to the 3' end of a newly synthesized mRNA molecule
RNA splicing
process in which intron sequences are excised from RNA molecules in the nucleus during the formation of a mature messenger RNA.
snRNA (small nuclear RNA)
RNA molecule of around 200 nucleotides that participates in RNA splicing
Translation initiation factors
protein that promotes the proper association of ribosomes with mRNA and is required for the initiation of protein synthesis
Genetic Code
set of rules by which the information contained in the nucleotide sequence of a gene and its corresponding RNA molecule is translated into the amino acid sequence into a protein. codon=amino acid.
Codon
group of three consecutive nucleotides that specifies a particular amino acid or that starts or stops protein synthesis. applies to the nucleotides in an mRNA or in a coding sequence of DNA
Anticodon
set of three consecutive nucleotides in a transfer RNA molecule that recognizes through base pairing the three nucleotide codon on a messenger RNA molecule. this interaction helps to deliver the correct amino acid to a growing polypeptide chain
Reading frame
one of the three possible ways in which a set of successive nucleotide triplets can be translated into proteins depending on which nucleotide serves as the starting point.
Aminoacyl-tRNA synthetase
during protein synthesis an enzyme that attaches the correct amino acid to a tRNA molecule to form a charged aminoacyl-tRNA.
Differentiation
process by which a cell undergoes a progressive coordinated change to a more specialized cell type brought about by large scale changes in gene expression
Promoter
DNA sequence that initiates gene transcription. includes sequences recognized by RNA polymerase. transcriptional switches allow cells to to respond to changes in their environment.
Transcription regulators
protein that binds specifically to a regulatory DNA sequence and is involved in controlling whether a gene is switched on or off. control gene expression from a distance. help initiate transcription by recruiting chromatin modifying proteins. can trigger the formation of an entire organ.
Transcriptional Activator
a protein that binds to a specific regulatory region of DNA to permit transcription of an adjacent gene. turns genes on.
Transcription Repressor
a protein that binds to a specific regulatory region of DNA to prevent transcription of an adjacent gene. turns genes off
Combinatorial control
describes the way in which groups of transcription regulators work together to regulate the expression of a single gene. eukaryotic genes are controlled by combinations of transcription regulators. can also generate different cell types.
Post transcriptional control
regulation of gene expression that occurs after transcription of the gene has begun like RNA splicing
Regulatory RNA
RNA molecule that plays a role in controlling gene expression. controls the expression of thousands of genes.
siRNA (small interfering RNA)
short length of RNA produced from double stranded RNA during the process of RNA interference. it base pairs with identical sequences in other RNAs leading to the inactivation or destruction of the target RNA. produced from double stranded, foreign RNAs to protect cells from infection.
miRNA (microRNA)
small noncoding RNA that controls gene expression by base pairing with a specific mRNA to regulate its stability and its translation. direct the destruction of target mRNAs.
Epigenetic inheritance
the transmission of a heritable pattern of gene expression from one cell to its progeny that does not involve altering the nucleotide sequence of the DNA. allows differentiated cells to maintain their identity.
Stem cells
relatively undifferentiated, self renewing cell that produces daughter cells that can either differentiate into more specialized cell types or an retain the developmental potential of the parent cell. specialized cells that are experimentally reprogrammed.
Chromatin remodeling
changes in nucleosome structure allow access to DNA for DNA and RNA synthesis.
Topoisomerase
released torsional stress by making a break in one strand ahead of helicase.
Telomerase
replicates the ends of eukaryotic chromosomes
Ribosome composition
4 rRNA (82 different proteins). 2/3 rRNA and 1/3 protein by weight.
Ribozyme
an RNA enzyme that catalyzes a chemical reacting. found in ribosomes.
Stop Codon
binds release factor not loaded with an amino acid. terminates translation.