CSUF Biol 151 Exam 2

What are nucleic acids?

polymers consisting of nucleotide monomers

What three things are nucleotides made of?

a phosphate group, a 5 carbon sugar, and a nitrigenous base

True of false: the nitrogenous base in a nucleotide is comparable to the r groups in amino acids

true

What are nucleotide monomers held together by

covalent bonds called phosphodiester bonds

Do nucleic acids have chemically distinct ends? If so, what are they?

yes, 5’ and 3’

What is complementary base pairing

hydrogen bond formation between nitrogenous bases

What is anti parallel arrangement

the orientation of the twiostrands of a molecule of dna

What is Chargaff’s rule?

Purines and Pyrimidines exist in a 1:1 ratio

DNA twists to form what?

forms an alpha helix with a major and a minor groove

How is DNA packaged within a cell?

into chromosomes

What is a chromosome made of?

chromatin

What are histones

DNA binding proteins

What is a nucleosome

DNA wrapped around a set of histones

What do genes provide?

information to build proteins

Where are genes present?

in all cells of an individual

How are genes inherited

from parent to offspring

Why is dna replication important

cells need to be able to copy their genetic material every time they divide

What occurs during DNA replication

1. DNA ‘unzips’

2. DNA unwinds

3. The original DNA strands function as templates for the addition of new, complementary nucleotides

4. Phosphodiester bonds link the nucleotides together

5. The process repeats until the entire molecule of DNA is copied

True or False: DNA replication is semi conservative

true

What is the Origin of replication (ORI)

the site where DNA starts

How many origins of replication do prokaryotes have

one

How many origins of replication do eukaryotes have

many

What is the function of Topoisomerase

inwinds dna, keeps a supercoil from forming

What is the function of DNA Helicase

separates the dna strands

What is the function of single stranded binding proteins

to stabilize the dna while it is unfolded and unattached

What is the function of primase

-adds RNA primer that tells DNA polymerase 3 where to attach

-connect okazaki fragments

-remove rna primer and replace it with dna

What is the function of DNA polymerase III

catalyzes formation of the new DNA strand using the original strand as its template

DNA Replication step 1

Enzymes unwind the double helix

DNA replication step 2

Proteins stabilize the unwound DNA

DNA replication step 3

The leading strand is synthesized continuously by DNA polymerase 3

DNA Replication step 4 (lagging strand)

The lagging strand is synthesized discontinuously. RNA primase synthesizes a short RNA primer primase, which is then extended by DNA polymerase 3

DNA replication step 5 (lagging strand)

DNA polymerase 1 removes the RNA primers and replaces it with DNA

DNA replication step 6 (lagging strand)

DNA ligase links the individual Okazaki fragments together to make a single long strand of DNA

Which way does the leading strand go?

5"‘ to 3’

Which way does the lagging strand go?

3’ to 5’

What is mismatch repair?

when an enzyme takes out and then replaces a single piece of dna

What is excision repair?

when an ezyme takes out an entire section of dna and then replaces it

What is the central dogma

the flow of information from DNA to proteins

Transcription describes…

the process of copying information exactly as it is written without modification

Transcription involves..

the enzume RNA polymerase catalyzing the formation of a molecule of mRNA using the template strand of DNA

RNA polymerase catalyzes the synthesis of a strand of what

mRNA with a 5’ to 3’ orientation

True or false: the mRNA product is complementary to the template strand

true

What role do hydrogen bonds play in transcription

stabilize the RNA nucleotides to the template strand

What controls whether a gene is transcribed or not

promoter regions in the DNA and transcription factors

What does transcription generate in eukaryotes

a primary mRNA transcript that is spliced to form the mature mRNA

True or false: RNA splicing occurs in both prokaryotes and eukaryotes

False, it only occurs in eukaryotes

In RNA splicing, what is taken out and what is kept to form a mature mRNA molecule

introns are removed, exons are kept and joined together

Which RNA protein complex completes splicing of the primary sequence

snRNP (snurp)= small nuclear ribonucleic protein

What must the snRNP’s be doing during splicing?

adding a 5’ methyl cap and a 3’ poly-A tail

What is protein synthesis

the story of how information encoded in a sequence of nucleotides is translated into a “different language”

The information in mRNA comes from what

the coding strand of DNA

What is mRNA organized into

units called codons

What are the three stop codons:?

UAA, UAG, UGA

When does protein synthesis happen?

When tRNAs bring amino acids to the ribosome

What is tRNA charging

when tRNA must be loaded with the appropriate amino acid before it can be used during translation

Does tRNA require atp

yes, it requires atp and enzymes called aminoacyl-tRNA synthetases

How many sites are there in translation? What are they called? In what order do they appear in?

3 sites, A, P, and E in that order

remember APE

What three steps is translation made up of

Initiation, elongation, and termination

What happens during initiation?

mRNA and ribosomes assemble (starts with the start codon AUG)

What two things happen during elongation?

Charged tRNA carrying an amino acid enters at the A site, and GTP is consumed when codon and anticodon are matched

What moves along the length of mRNA and tRNA to allow it to make the protein

ribosomes

What happens during termination?

it occurs when a stop codon is reached, release factors bind to the stop codon and break teh bond between the tRNA and the polypeptide

What are the three types of cell division

binary fission, mitosis, and meiosis

What is required before mitosis can happen?

replication of all the chromosomes

What is a karyotype

the genetic information in an organism

What happens in the first phase of mitosis

replicated DNA form chromosomes with two sister chromatids held together at the centromere

What are the 5 phases of mitosis (in order)

prophase, prometaphase, metaphase, anaphase, telophase&cytokinesis

What occurs during prophase?

chromatin condenses to form sister chromatids, the mitotic spindle begins to form

What happens during prometaphase

nuclear envelope breaks down, mitotic spindle fibers contact chromosomes at kinetochores and connect to centrosomes

What happens during metaphase

chromosomes complete migration to the middle of a cell (the metaphase plate)

What happens during anaphase

sister chromatids separate into daughter chromosomes which are pulled to opposite ends of a cell by spindle fibers

What happens during telophase

nuclear envelope reforms and chromosomes de condense

followed by cytokinesis

What phase do cells spend most of their life in

interphase

What is the cell cycle?

Interphase+M phase

What makes up interphase

G1 phase, S phase, and G2 phase

What happens in G1 phase

Normal functions of the cell: grow, make proteins and ATP, etc

What happens in s phase

DNA is replicated

What happens in G2 phase

Growth and preparation for cell division

What controls the transition form one stage to the next

Cyclins

True or false: Cyclin must bind to CDK to make it an active kinase that can phosphorylate things

True

True or false: the type and amount of cyclin does not change

false, it varies over time

What does activated CDK start

a signal cascade

What is social control

cells in multicellular organisms tell each other when to divide by using growth factors

What triggers signal cascades

growth factors

The loss of quality control of the cell cycle can lead to what

cancer

What is apoptosis

a safe way to remove cells

What is cancer

the result of unregulated growth and division of a cell