B1: beginning to DNA + RNA

what is a polymer?

chain made up repeating, similar parts

long repeating chain of individual subunits called monomers

what is a monomer?

single part of the chain

what are some examples of polymers? what are their monomers?

polysaccharides: chains of monosaccharides (sugars)

nucleic acids: chains of nucleotides

proteins: chains of amino acids

starches vs. fats: which is a denser form of storage?

fats

per unit weight, fats store 2-6 times more energy than carbohydrates → have a lot of potential energy

starches vs. fats: which is more easily utilized?

starch

• relatively easy to break down into sugar monomers and catabolize → convenient form of energy storage

fats

• getting energy out is comparatively slow → hard to create fats and metabolize energy from fats

starches vs. fats why might bacteria prefer one over the other

starch

• most bacteria don’t bother using fats to store energy because it’s so slow

what are some important structural components that use starch?

cell wall components:

• peptidoglycan (bacteria)

• cellulose (plants)

• chitin (fungi)

lipopolysaccharides, glycocalyx (capsule)

modifies proteins and fats (glycoproteins, glycolipids)

what are some important structural components that use fats?

phospholipids to make membranes

modifications: lipoproteins, lipopolysaccharides

define the central dogma of biology

DNA (blueprint) → RNA (photocopies) → protein (machines)

what is the role of DNA?

has the permanent version of all designs for the cell

must be long-lasting

must be protected

what is the role of RNA?

short-lived copies of DNA

like a photocopy of DNA that can be passed around

what is the role of proteins?

workers and machines that operate processes in the cell

made by “reading” the RNA

what are the building blocks of DNA?

nucleotides

what is the structure of nucleotides?

deoxyribose

phosphate group

nitrogen-containing (purine/pyrimidine) bases:

• adenine (A)

• guanine (G)

• thymine (T)

• cytosine (C)

what is the structure of DNA?

double helix

what are the rules of base pairing?

A hydrogen bonds with T

C hydrogen bonds with G

why is it beneficial that the bases are hydrogen bonded?

easier to break

what is semi-conservative replication?

the 2 new DNAs are both 50% original DNA and 50% new DNA

what are DNA polymers built by?

DNA polymerase

describe the process of DNA replication

DNA polymerase uses a template strand to read and create a new DNA strand that is complementary to the template strand

compare prokaryotic and eukaryotic origins of replication

prokaryotes have ONE origin of replication on their circular chromosome

eukaryotes have MANY origins of replication spread our across their linear chromosomes

what are the building blocks of RNA?

nucleotides

what does the nucleotides consist in RNA?

ribose

phosphate group

nitrogen-containing (purine/pyrimidine) bases:

• adenine (A)

• guanine (G)

• uracil (U)

• cytosine (C)

what is the structure of RNA?

single stranded

what are the 4 bases in RNA? which one is different from DNA?

A hydrogen bonds with U

C hydrogen bonds with G

has uracil (U) instead of thymine (T)

what is transcription? what enzyme does it use?

process that creates RNA

uses an enzyme called RNA polymerase

describe the process of transcription?

RNA polymerase reads one of the strands and makes a complementary RNA molecule

when transcription is done, the RNA transcript floats off, and the DNA snaps back together

transcription vs. DNA replication: where does it occur?

DNA replication: happens in only a few (one in prokaryotes) spots

RNA transcription: happens in many thousands of places across the chromosomes

transcription vs. DNA replication: what gets created?

DNA replication: creates 2 identical copies of the entire chromosome

RNA transcription: creates a copy of a portion of only one strand of DNA

transcription vs. DNA replication: how long does the copy last?

DNA replication: permanent copy that lasts for the life of the cell

• must remain safe so it can be passed on to offspring

RNA transcription: temporary copy, lasting for as long as several hours or as short as a few minutes

transcription vs. DNA replication: what do the chromosomes contain when DNA is replicated?

have the plans for every contingency or situation stored up

transcription vs. DNA replication: what do the RNA copies contain during transcription?

plans that are needed right now by the cell

what is a gene?

segments of DNA that are transcribed

what are the parts of a gene?

promoter

coding sequence

terminator

transcripts that will go on to make proteins are called what?

messenger RNA

steps of transcription with respect to genes: promoter binding

Once RNA polymerase finds the promoter → unwinds the DNA in that region

steps of transcription with respect to genes: initiation

RNA polymerase then grabs the template strand and reads it, generating the RNA transcript

steps of transcription with respect to genes: elongation

as RNA polymerase moves down, it has a transcription bubble (opens in the RNA polymerase and closes behind it)

steps of transcription with respect to genes: termination

RNA polymerase hits the terminator and is knocked off the DNA → transcript is released