Cell Bio lecture 6 Flashcards
(24 cards)
when a particular protein is needed by the cell, what happens?
the nucleotide sequence of the appropriate segment of DNA molecule is first copied into another type of nucleic acid-RNA (ribonucleic acid)
the segment of DNA used to copy is called a
gene
the resulting RNA copies are used to direct …
the synthesis of the protein
how often are conversions from DNA to protein made in each cell in the body?
thousands every second
the flow of genetic information in cells:
DNA to RNA to protein
the flow of genetic information in cells is called
central dogma- express genetic info
process by which cells used to copy DNA into RNA
transcription
process by which cells use the information in RNA to make protein is called
translation
the first step in gene expression
transcription
transcription is the process
by which cells read out the instructions in their genes
many RNA copies can be made from
the same gene
For most genes, RNA serves solely as an intermediary on the pathway to making a protein. For those genes,
each RNA molecule can direct synthesis, or translation, of many identical protein molecules
Each gene can be transcribed and its RNA translated, at _ _, providing the cell with
different rates, with a way to make vast quantities of some proteins and tiny quantities of others. In addition, a cell can regulate the expression of each of its gene according to the needs of the moment
the first step a cell takes in expressing one of its many thousands of genes is to
copy the nucleotide sequence of that gene into RNA in transcription. This process is catalyzed by an enzyme called RNA polymerase
like DNA, RNA is a __ made of__, linked by__
linear polymer, 4 different nucleotides, phosphodiester bonds
sugar differences between RNA and DNA
ribose, OH bottom right of pentagon. deoxyribose, H bottom right
base differences between RNA and DNA
top left, H attached in RNA, methyl attached in DNA
U base pairs with A via
hydrogen bonding
Whereas DNA occurs in cells as a double stranded helix, RNA is largely single stranded. RNA folds…
up into a variety of 3D shapes, which allows RNA to play various structural, regulatory, and catalytic roles.
transcription begins with the
opening of a small portion of the DNA double helix to expose the bases on each DNA strand
the strands in transcription produces RNA complementary to DNA
one of the two strands of the DNA double helix then serves as a template for the synthesis of RNA
ribonucleotides are added, one by one to
the growing RNA chain
the nucleotide sequences of the RNA chain is determined by
complementary base-pairing with the DNA template strand
when a good match is made, the incoming ribonucleoside triphosphate is linked via
the phosodiester bonds to the growing RNA chain by the enzyme RNA polymerase. The RNA chain produced by transcription-the RNA transcript-therefore has a nucleotide sequence complementary to the strand of DNA used as the template
