BMB 280 Exam 3

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Terms in this set (...)

germ cells
carry a copy of its genome to the next generation of organisms
somatic cells
are doomed to die without leaving evolutionary descendants of their own
point mutations
are caused by failures of the normal mechanisms for copying and repairing DNA aka changes that affect a single nucleotide pair; they CAN change the regulation of a gene
gene duplications +divergence
give rise to families of related genes each with a specialized function within a single genome
pseudogene
a gene that loses function due to mutation
exon shuffling
novel genes are created by ___ ____;
mobile genetic element
___ ___ ___ DNA sequences that can move from one chromosomal location to another; the evolution of genomes has been profoundly influenced by the movement of these; they encode the components they need for movement
horizontal gene transfer
genes can be transfered between organisms by __ ___ __ aka sexual reproduction
homologous genes
...
transposons
aka mobile genetic elements; are typically classified according to the mechanism by which they move or transpose
SNPs (single-nucleotide polymorphisms)
most of the genetic variation in the human genome takes the form of single base changes called ___; they are simply points in the genome that differ in nucleotide sequence between one portion of the population and another
central dogma
the principle that genetic information flows from DNA to RNA to protein(provides a mechanism for heredity)
chromosomes
long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism;become visible as a distinct entity when a plant or an animal cell prepares to divide
DNA double helix
typical structure of of a DNA molecule in which the two complementary polynucleotide strands are wound around in each other with base-pairing between the strands
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
telomere
repetitive nucleotide sequence that caps the ends of linear chromosomes(counteracts the tendency of the chromosome otherwise to shorten with each round of replication)
centromere
specialized DNA sequence that allows duplicated chromosomes to be separated during M phase; attachment site to mitotic spindle for segregation
nucleolus
site where ribosomal RNA is transcribed and ribosomal subunits are assembled
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
histone
on of a group of abundant highly conserved proteins around which DNA wraps tor form nucleosomes (represent the most fundamental level of chromatin packaging)
DNA replication/synthesis
base pairing enables ____ _____;the process by which a copy of a DNA molecule is made
DNA polymerase
__ ___ is self-correcting(but it cannot initiate DNA synthesis alone); sythensizes DNA using a parental strand as template, primary role to form phopho-ester linkage at 3' end
DNA helicase
"unzips" DNA strands from each other
DNA primase
an RNA polymerase that uses DNA as a template to produce an RNA fragment that serves as a primer for DNA synthesis
DNA ligase
enzyme that reseals nicks that arise in the backbone of a DNA molecule(connects 5' and 3' ends)
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
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)
depurination
a spontaneous reaction in which purine bases (A and G) are lost; it does not break the DNA phosphodiester backbone but instead removes a purine base from a nucleotide
deamination
spontaneous loss of an amino group from a cytosine in DNA to produce the base uracil
transcription
process in which RNA polymerase uses one strand of DNA as a template to synthesize a complementary RNA sequence
translation
process by which the sequence of nucleotides in a messenger RNA molecule directs the incorporation of amino acids into protein
RNA polymerase
enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using nucleoside triphosphate precursors
mRNA (messenger RNA)
RNA molecule that specifies the amino acid sequence of a protein
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
rRNA (ribosomal RNA)
RNA molecule that forms the structural and catalytic core of the ribosome
RNA processing
broad term for the modifications that a precursor mRNA undergoes as it matures into an mRNA. typically includes 5' capping, RNA splicing, and 3' polyadenylation
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
intron
noncoding sequence within a eukaryotic gene that is transcribed into an RNA molecule but is then excised by RNA splicing to produce an mRNA
splicesome
large assembly of RNA and protein molecules that splices introns out of pre-mRNA in the nucleus of eukaryotic cells
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 in a protein
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 three possible ways in which a set of successive nucleotide triplets can be translated into protein, 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
transcription regulators
proteins that bind specifically to a regulatory DNA sequence and is involved in controlling whether a gene is switched on or off
transcription activator
a protein that binds to a specific regulatory region of DNA to permit transcription of an adjacent gene
transcription repressor
a protein that binds to a specific regulatory region of DNA to prevent transcription of an adjacent gene
combinatorial control
describes the way in which groups of transcription regulators work together to regulate the expression of a single gene
post-transcriptional control
regulation of gene expression that occurs after transcription of the gene has begun; examples include RNA splicing and RNA interference
regulatory RNAs
RNA molecules that play a role in controlling gene expression
small interfering RNA (siRNA)
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
microRNA (miRNA)
small noncoding RNA that controls gene expression by base-pairing with a specific mRNA to regulate its stability and its translation
epigentic 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
stem cells
relatively undifferentiated, self-renewing cells that produce daughter cells that can either differentiate into more specialized cell types or can retain the developmental potential of the parent