DNA structure
what is the central dogma of biology?
DNA-transcription-RNA-translation-protein
What does DNA stand for?
deoxyribonucleic acid
what is the sugar present in DNA?
deoxyribose sugar
what is the structure of DNA?
double helix made of 2 strands, held together by hydrogen bonds between bases and has a sugar-phosphate backbone with nitrogenous bases on the interior
What is "proofreading"?
ensures new strand is complementary to origninal strand by checking for errors by removing nucleotides
what are the 3 components of the nucleotide?
phosphate group, sugar, nitrogen base
DNA replication is.....
semiconservative
what does DNA do?
stores genetic information + instructions required for an organism to develop, grow, and function
what is semi-conservative replication?
the two strands of DNA unwind from each other, and each acts as a template for synthesis of the new complementary strand. This results in two DNA molecules with one original and one new strand (daughter strand).
what would happen if DNA was not replicated prior to cell division?
there wouldn't be enough genetic material to produce two cell with the genetic code necessary for life's functions
If you wanted to use a radioactive or fluorescent tag to label only the DNA in a cell and not the RNA, what molecules would you label?
thymine, deoxyribose sugar
what are the 3 types of RNA and their function?
1) Messenger RNA: carried copy of genetic information from nucleus to ribosomes for protein synthesis 2)Ribosomal RNA: makes up ribosome along with other proteins 3)Transfer RNA: carries amino acid across to ribosome to form protein chain
What are the nucleotide bases present in DNA?
Adenine, Thymine, Guanine, and Cytosine
What are the nucleotide bases present in RNA?
Adenine, Uracil, Guanine, and Cytosine
what is chargraff's rule?
Chargraff found that the base composition varies between species but that within a species the percentage of "A" and "T" bases and the percentage "G" and "C" bases are equal.
why does DNA have to be tightly packaged up?
DNA is very long, if it were not tightly packaged it could not fit inside of the nucleus
what is conservative replication?
DNA replication results in one molecule that consists of both original DNA strands (identical to the original DNA molecule) and another molecule that consists of two new strands (with exactly the same sequences as the original molecule)
what is dispersive replication?
DNA replication results in two DNA molecules that are mixtures, or "hybrids," of parental and daughter DNA. In this model, each individual strand is a patchwork of original and new DNA.
what is the complementary DNA sequence?
G, A, A, T, C, C, G ,T ^ ^ ^ ^ ^ ^ ^ ^ C T T A G G C A
During DNA replication what does each strand act as?
a template for the formation of a new double helix
what does chargraff's rule say?
adenine matches with thymine and guanine matches with cytosine
The two strands of DNA are....
antiparallel
what rule ensure that the two new DNA strands are identical to the original strand?
base pairing rule (Chargaff's rule)
explain what semi-conservative replication means?
each chromatid contains half original (parent) DNA and half new (daughter) DNA
how are the new strands of DNA lengthened?
free nucleotides are added to the new strand by enzymes
what kind of bonds link nitrogen bases?
hydrogen
what is the purpose of the centromere?
keeps sister chromatids together in an organized way until they are separated prior to nuclear division
what is the purpose of DNA replication?
prepares a chromosome for cell division by producing two chromatids which are identical copies of the genetic material
what is RNA and what does it do?
ribonucleic acid; helps DNA make proteins
What is the sugar present in RNA?
ribose sugar
why does one strand of DNA need to be copied in segments?
the strands of antiparallel and the enzymes only work in one direction, so one strand must be copied in pieces as the DNA unwinds
how is DNA packaged in eukaryotes?
tightly packaged within a chromosome
What is the DNA helix made of?
two intertwined sugar and phosphate chains, linked by bases
if you wanted to use a radioactive or fluorescent tag to label only the RNA in a cell and not the DNA, what molecules would you label?
uracil, ribose sugar
what does a replicated chromosome look like?
x-shape
what are the 3 enzymes in DNA replication and their function?
•Helicase: breaks hydrogen bonds between DNA strands to "unzip" helix •Polymerase: creates new complementary strand •Ligase: joins together fragments to make continuous strands
name and describe the two steps of DNA replication
•Unzipping: helicase enzyme breaks hydrogen bonds between DNA strands to "unzip" helix •Copying: each parental strand serves as a template that determines order of nucleotides on a new complementary strand
what are the 5 different kinds of nitrogen bases?
•adenine •guanine •cytosine •thymine (DNA only) •uracil (RNA only)
