biochemistry of the genome Flashcards
what plant did Mendel use in his experiments
diploid garden pea
why did he use the pea plant
it naturally self fertilizes and is highly inbred and always produce offspring that look like the parent
what are nucleic acids composed of
monomers called nucleotides that are polymerized to form large strands
what is the base sequence of dna responsible for
carrying and retaining the hereditary information in a cell
what are deoxyribonucleotides
nucleotides that compose dna
what are the components of a deoxyribonucleotides
a five carbon sugar (deoxyribose)
a phosphate group
a nitrogenous base
what is a nitrogenous base
a nitrogen containing ring structure that is responsible for complementary base pairing between nucleic acid strands
what nitrogen bases are purines
adenine and guanine
describe a purine
they have a double ring structure with a six carbon ring fused to a five carbon ring
what nitrogen bases are pyrimidines
cytosine and thymine
describe pyrimidines
they are smaller nitrogen bases that only have a six carbon ring structure
how do nucleoside triphosphates combines
by covalent bonds known as 5’-3’ phosphodiester bonds
what is a 5’-3’ phophodiester bond
linkages whereby the phosphate group attached to the 5’ carbon of the sugar of one nucleotide bonds to the hydroxyl group of the 3’ carbon of the sugar of the next nucleotide
what does phosphodiester bonding form
sugar-phosphate backbone the framework of nucleic acid strand
what is used during the polymerization process
deoxynucleotide triphophates (dNTP)
how is a sugar phosphate backbone constructed
the two terminal phosphates are released from the dNTP as a pyrophosphate
the resulting strand of nucleic acid has a free phosphate group path the 5’ carbon end and a free hydroxyl group at the 3’ carbon end
the two unused phosphate groups from the nucleotide triphosphate are released as pyrophosphate during the phophoidester bond formation
the pyrophosphate is hydrolyzed releasing the energy to drive nucleotide polymerization
get a YouTube video
what does it mean that dna strands are antiparallel
the 3’ end of one strand faces the 5’ end of the other
what does the 3’ end have
a free hydroxyl group
what does the 5’ end have
a free phosphate group
what do complementary base pairs take place between
a purine and a pyrimidine
what are the complementary base pairs
adenine and thymine
cytosine and guanine
what stabilizes the base pairs
hydrogen bonds
how many hydrogen bonds between thymine and adenine
2
how many hydrogen bonds between guanine and cytosine
3
how is dna denatured
heat separates the two strands
how is single stranded dna put back together
by reannealing or denaturing by cooling or removing chemical denaturants allowing hydrogen bonds to reform
what dna is easier to denature
hydrogen bonds between cytosine and guanine
What is vertical gene transfer
the transmission of information from mother to daughter cells
How is RNA structure different from DNA
RNA is shorter and usually single stranded
what is RNA linked by
phophodiester bonds
what does a ribonucleotide chain consist of
ribose, on of the four nitrogen bases and a phosphate group
what is the RNA specific pyrimidine
uracil
what does uracil pair with
adenine instead of thymine
what types of RNA are involved in protein synthesis
mRNA
rRNA
tRNA
what does mRNA serve as
a photocopy of specific information needed at a particular point in time that serves as instructions to make a protein
what does mRNA do
carries the message from DNA, the interacts with ribosomes and other cellular machinery to direct synthesis of the protein it encodes during the process of translation
what is transcription
synthesizing of mRNA
what are the stable types of RNA
rRNA
tRNA
where does synthesis, cutting and assembly of rRNA take place in eukaryotes
the nucleolus region of the nucleus
where does synthesis, cutting and assembly of rRNA take place in prokaryotes
cytoplasm
what are ribosomes composed of
rRNA and protein
what percent of a ribosome is rRNA
60% by mass and provides the location where mRNA binds
what does rRNA do
ensures proper alignment of mRNA, tRNA and robosomes
has enzymatic activity to catalyze the formation of peptide bonds between tow aligned amino acids during protein synthesis
what is the smallest RNA and how long is it
tRNA 70-70 nucleotides
what does tRNA do
carries the correct amino acid t the site of protein synthesis in the ribosome
what allows for the correct amino acid to be inserted in the polypeptide chain being synthesized
the base pairing between rRNA and mRNA
describe structure of mRNA
Short, unstable, single-stranded RNA corresponding to a gene encoded within DNA
describe the function of mRNA
Serves as intermediary between DNA and protein; used by ribosome to direct synthesis of protein it encodes
describe the function of rRNA
Longer, stable RNA molecules composing 60% of ribosome’s mass
describe the function of rRNA
Ensures the proper alignment of mRNA, tRNA, and ribosome during protein synthesis; catalyzes peptide bond formation between amino acids
describe the structure of tRNA
Short (70-90 nucleotides), stable RNA with extensive intramolecular base pairing; contains an amino acid binding site and an mRNA binding site
describe function of tRNA
Carries the correct amino acid to the site of protein synthesis in the ribosome
what does double stranded RNA indicate
a virus
what is an example of a double stranded RNA
rotavirus
what are genes
segments of DNA molecules
what is a genotypes
the full collection of genes that a cell has in its genome
what is a phenotype
genes being expressed at any given point in time determining a cells activities and observable characteristics
what are constitutive genes
genes that are always expressed, they are necessary the basic functions of the cell
what factors may change the phenotype of a cell
changes in temperature or nutrient availability
what are chromosomes
discrete dna structures within cells that control cellular activity
what does it mean for a chromosome to be diploid
the cell contain two copies of each chromosome
how long is the human genome if stretched out
2 meters
what is DNA supercoiling
the process where DNA is twisted to fit inside the cell
what is an underwound dna
less than one turn of the helix per 10 base pairs
what is overwound dna
more than one turn per 10 base pairs
what does topoisomerase do
helps maintain the structure of supercoiled chromosomes to prevent overwinding of dna during certain process like dna replication
what are histones
dna binding proteins that do dna wrapping and attachment to scaffolding proteins
what is chromatin
the combination dna with attached proteins
what. can influence the packaging of dna by histones in eukaryptes
the presence of methyl groups on certine cytosine nucleotides of dna
what is epigenetics
a mechanism for regulating gene expression without altering the sequence of nucleotides
what makes prokaryotes haploid
they contain only one copy of each gene
what is DNA gyrase
a type of topoisomerase found in bacteria and some algae that helps prevent overwinding of DNA
two examples of bacteria that can cause chromatin remodeling in host
h. pylori
shigella
what is noncoding dna
dna that does not encode proteins or stable RNA products
where is noncoding dna found
areas prior to the start of coding sequences of genes and intergenic regions (area between genes)
what is an example of an extrachromosomal virus
HPV
what are plasmids
small loops of dna that may contain one or few genes that are not essential for normal growth in prokaryotes
how are plasmids exchanged between bacteria
horizontal gene transfer
what are the clinical implications of plasmids
they encode virulence factors
make microbes resistant to certain antibiotics
used in genetic engineering and biotechnology to move genes from one cell to another
Frederick Griffith infected mice with a combination of dead R and live S bacterial strains. What was the outcome, and why did it occur?
The mice will die. Transformation was not required.
Why was the alga Acetabularia a good model organism for Joachim Hämmerling to use to identify the location of genetic material?
It is a large, asymmetrical, single cell easy to see with the naked eye.
Which of the following best describes the results from Hershey and Chase’s experiment using bacterial viruses with 35S-labeled proteins or 32P-labeled DNA that are consistent with protein being the molecule responsible for hereditary?
After infection with the 35S-labeled viruses and centrifugation, only the pellet would be radioactive.
Which method did Morgan and colleagues use to show that hereditary information was carried on chromosomes?
correlations between microscopic observations of chromosomal movement and the characteristics of offspring
According to Beadle and Tatum’s “one gene–one enzyme” hypothesis, which of the following enzymes will eliminate the transformation of hereditary material from pathogenic bacteria to nonpathogenic bacteria?
deoxyribonucleases
Which of the following is not found within DNA?
amino acids
If 30% of the bases within a DNA molecule are adenine, what is the percentage of thymine?
30
Which of the following statements about base pairing in DNA is incorrect?
Adenine binds to guanine.
During denaturation of DNA, which of the following happens?
Hydrogen bonds between complementary bases break.
Which of the following types of RNA codes for a protein?
mRNA
A nucleic acid is purified from a mixture. The molecules are relatively small, contain uracil, and most are covalently bound to an amino acid. Which of the following was purified?
tRNA
Which of the following types of RNA is known for its catalytic abilities?
rRNA
Ribosomes are composed of rRNA and what other component?
Protein
Which of the following may use RNA as its genome?
a virus
Which of the following correctly describes the structure of the typical eukaryotic genome?
diploid
