test 2 Flashcards
molecular components of DNA
adenine, cytosine, guanine, thymine; deoxyribose (pentose) is the phosphate background (sugar)
molecular components of RNA
adenine, cytosine, guanine, uracil; ribose (pentose) is the phosphate background (sugar)
nucleotide
base+sugar+phosphate= nucleotide
how can nucleotides be measured
by distance and length
DNA and RNA strands
nucleotide+ nucleotide(n)= strand
deoxyribonucleotides; ribonucleotides
DNA
double stranded; double helix; hydrogen bonds enable the ladder and hold the helix together, bonds can be broken; one sequence predicts the next one; complex macromolecules made of several basic atomic components; encodes genes
DNA hierarchical arrangement
dna from each parent arranged into chromosomes (23 chromosomes from each) 22 pairs of autosomes and 1 pair of sex chromosomes
replication
process through which DNA serves as the template for the synthesis of RNA
transcription
process through which DNA serves as the template for the synthesis of RNA
what causes bonds to break
increase in temperature and pH
DNA replication
relies on complementary base pairing ; occurs before mitosis and meiosis 1; semi conservative; DNA is synthesized by DNA polymerase in a 5’ to 3’ direction
what is DNA polymerase responsible for
synthesizing a new strand of DNA during replication
helicase
surrounds and separates enzyme
where are the genes
indicated by start (ATG) and stop (TAA, TGA, TAG) codones; hold the code for specific protein
transcription
relies on base pairing; RNA is synthesized by RNA polymerase 2
RNA processing in eukaryotic cells
splicing out of introns, capping with 5’ methyl cap, polyadenylation
translation
ribosomes make proteins from the messages encoded in mRNA; three nucleotide groups called codons encode one amino acid (genetic code)
genetic code
each 3-nucleotide mRNA codon specifies a particular amino acid; each tRNA transfer a particular amino acid
mRNA
template for the production of proteins, the molecules that build and comprise structures and perform enzymatic reactions
tRNA
enables the transfer of amino acids into a growing polypeptide chain
rRNA
a component of protein producing ribosomes
the chromosome
each in a living cell is a DNA double helix; in the cell nuclei of higher organisms usually linear (larger, complex); some of bacteria are circular
*gene, nucleotide, genome, chromosome (smallest to largest)
viral genomes
some made of DNA, others RNA; some single stranded, others double stranded; some integrate their genetic material into the host cell’s genome; small, no introns and complex
eukaryotic genomes
made of DNA; contain introns and exons; frequently include several to many linear chromosomes; size varies
overlapping genes
are read from two different starting points or in opposite directions from a segment of DNA; common to many species, including humans; 1 gene=1 protein; not evenly distributed; gene poor or gene rich
gene
short segment of DNA that contains the code or blueprint for one or more proteins
prokaryotic genomes
made of DNa; circular or linear; do not contain organelles; float freely inside the cell; size varies
human genome
23 pairs of chromosomes (diploid); 1-22 are autosomes; X and Y are sex chromosomes; males are XY, females are XX; mitochondria in egg; 3 billion base of DNA; 1.5-3% codes for proteins; 35000-100000 genes; 99.9% identical at DNA level; alternation lead to disabilities
chromatin and DNA packaging
DNA would be 6.8 feet long if stretched out; packaged DNA is chromatin; wound tightly around histones”(bead on a string)*almost 2 meters tiny and thin
regulation of human genome
the expression of genes within an organism’s genome is tightly regulated by: promoters, enhancers, silencers, methylation, imprinting, alternative splicing, RNA stability; X-inactivation
promoters
bind RNA polymerase and initiate transcription
enhancers
increase transcription of associated genes
silencers
suppress transcription of associated genes
methylation
attachment of a methyl group to a cytosine base result in silencing of gene expression
imprinting
special case of methylation, occurs during gametogenesis
alternative splicing
allows for multiple proteins from one gene
RNA stability
cells control rates at which new mRNA’s are transcribed and the rate at which mRNA’s decay
x-inactivation
lionization; turns off most genes on some of the X chromosomes of females; occurs early in a female’s development; inactivated X chromosomes become compacted (Barr Body); random process
karyotyping
visual representation of a genome; variations in the number or structure of human chromosomes can cause a variety of genetic disorders; variations in numbers within the cell are called aneuploidies
extra copy of chromosome 21
down syndrome
extra copy of chromosome 13
patau syndrome
blending model
offspring are a blend of parents; blend of characteristics is passed on to the next generation; variation is washed out over time
particulate model
offspring are a combination of the parents; parental contributions are passed to the next generation as separate entities; variations is maintained over time
Mendel’s research
made pure breeding lines for different phenotypes of pea plants; crossed the pure lines to get F1 generation; recessive traits cannot be inherited through complete dominance only if parents are heterozygous for the trait
punnet square
bookkeeping tool; allele is the specific form of hereditary particle passed on through male or female gametes; if alleles for the dame gene are different in the same person the individual is heterozygous; useful for predicting the ratios of possible genotypes of a particular combination of alleles
Watson and crick
determined the structure of DNA
mendel
breeding experiment with pea plants
miescher
discovered DNA
levene
studied nucleotides, tetranucleotide hypothesis
chargaff
chargaff’s rules (A+G=T+C)
franklin
x-ray crystalography
new sequencing
454 pyrosequencing and illumine
the DNA instructional manual
each chromosome is a continuous strand of DNA; 3 billions ladders
met amino acid
AUG
DNA extraction
purified away from proteins and other cellular contaminates isolate DNA for: genetic testing; body identification, analysis of forensic evidence
