Bio 110:205 questions

Hershey and Chase

concluded that the genetic material of the bacteriophage was DNA, not protein.

Avery, MacLeod, McCarty

Determined that DNA was Griffith's "Transforming Factor."
Only DNase caused R to not transform to S
*DNA is genetic material

Griffith

discovered bacterial transformation
S. Pneumoniae

Chargoff

Determined that in a molecule of DNA there is an equal amount of A and T, and an equal amount of C and G

Meselson and Stahl

Determined that DNA replication is semiconservative.

Rosalind Franklin

Woman who generated x-ray images of DNA, she povided Watson and Crick with key data about DNA
Found Helical structure

Watson and Crick

Developed the double helix model of DNA.

Dr. Okazaki

Discovered lagging strand made as Okazaki fragments that have to be connected later

Beadle and Tatum

one gene one enzyme hypothesis

10% of the base pairs in a sample of DNA extracted from a eukaryote are adenine. What percent of guanine is found in this DNA sample?

40%

If a DNA template strand has a sequence of 3' TACAATGTAGCC 5', the RNA produced from it will be which sequence?

5'-AUGUUACAUCGG-3'

Binds the Okazaki fragments together

Ligase

Very accurate enzyme, it only makes a mistake 1/10,000 reactions. Makes DNA from a DNA template.

DNA Polymerase

RNA that has catalytic capabilities.

Snurps

Holds the replication fork open

single stranded binding proteins

Builds RNA using DNA as a template

RNA polyermase

Adds RNA primer at the beginning of the leading stand during replication

Primase

Reversibly binds to the A-site on the ribosome at a stop codon.

Releasing factor

Breaks hydrogen bonds and unwinds the DNA at the replication fork.

Helicase

Found at the center of two chromatids, aids in separation of the chromosomes or chromatids

Kinetochore

Alleviates knots ahead of replication fork made from separating action of helicase

Topoisomerase

any of several enzymes that break down the double-stranded or single-stranded DNA molecule into its component nucleotides.

DNase

A type of nuclease that catalyzes the degradation of RNA into smaller components.

RNase

an enzyme that breaks down proteins and peptides.

Protease

a compound structure at the end of a chromosome

Telomere

an enzyme that adds nucleotides to telomeres, especially in cancer cells.

telomerase

a short single strand of RNA that serves as a starting point for DNA synthesis. It is required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA.

RNA primer

any of a group of five small basic proteins, occurring in the nucleus of eukaryotic cells, that organize DNA strands into nucleosomes by forming molecular complexes around which the DNA winds.

Histone

Double ring (Adenine and Guanine)

purines

Single ring (Cytosine and Thymine/Uracil)

Pyrimidines

Phosphate group

pentose sugar- base binds to 1 C... clockwise... phosphate binds to 5 C

nitrogenous base

Nucleotides

a ribonucleoprotein complex that is the site in the cell nucleus where introns are excised from precursor messenger RNA and exons are joined together to form functional messenger RNA

Spliceosome

Transcribed but not translated (cut out)

Introns

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

Codon

a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA.

Anticodon

catalyzes the attachment of amino acids to tRNA

aminoacyl-tRNA synthetase

a simple organic compound containing both a carboxyl (—COOH) and an amino (—NH2) group.

amino acid

a virus that parasitizes a bacterium by infecting it and reproducing inside it.

bacteriophage

Why must the life cycle of sexually reproducing species alternate between haploid and diploid stages?

Meiosis must occur at some point in the life cycle to prevent a doubling of chromosomes in each generation.

Which of the following biological phenomena support Mendel's law of segregation?

Meiosis

If a man and woman are heterozygous for cystic fibrosis, what is the probability that they will have a boy that also has cystic fibrosis?

1/8

What is the origin of replication?

The site of start point of replication. Provides an opening called a replication bubble that forms two replication forks.

What is replication?

the process of copying DNA

Where does replication happen in Prokaryote?

cytoplasm

Where does replication happen in eukaryote?

nucleus

How is a DNA molecule structured?

Nucleotides are the building blocks of DNA (and RNA).
A strand of DNA (or RNA)
Two strands form a double helix. (DNA)
DNA is associated with an array of different proteins to form chromosomes.
A genome is the complete complement of an organism's genetic material
*two nucleobases bound to each other by hydrogen bonds.

DNA is semiconservative when it is built, what does this mean?

during DNA replication, each strand of DNA from the original cell is "conserved", or not changed, while a complementary copy is made from "new" nucleotides.
Left with 2 original + 2 new

What is the 5'-3' rule? What does it mean?

5' to 3' refers to the carbons
DNA is read from and built in a 5' to 3'(Carbon numbers)
But RNA is 3' to 5' because it's replicated

Describe the replication fork

The area where two DNA strands have separated and new strands are being synthesized. Replication proceeds outward from the two replication forks.

Describe the leading strand

- Synthesized by DNA polymerase 3!!!!
- It leads into the replication fork - leads refers to the new DNA
- Synthesized continuously in the 5' --\> 3' direction

Describe the lagging strand

- Synthesized by DNA polymerase 3 (a second copy)
- Synthesized away from the replication fork
- Synthesized discontinuously
- Has Okazaki fragments
- Synthesized 5' --\> 3'

What happens during initiation of DNA replication?

proteins bind to the origin of replication while helicase unwinds the DNA helix and two replication forks are formed at the origin of replication.

What happens during elongation of DNA replication?

a primer sequence is added with complementary RNA nucleotides, which are then replaced by DNA nucleotides.
the leading strand is made continuously, while the lagging strand is made in pieces called Okazaki fragments.

What happens during termination of DNA replication?

primers are removed and replaced with new DNA nucleotides and the backbone is sealed by DNA ligase.

What is a nucleosome?

Section of DNA wrapped around 8 histone protein cores inside a chromosome

What is the 30 nm fiber?

Nucleosomes units that are organized into a more compact structure that is 30 nm in diameter. Histone H1 and other proteins are important in the formation of the 30-nm fiber, which shortens the nucleosome structure another sevenfold. Linker regions in the 30-nm structure are variably bent and twisted, with little direct contact observed between nucleosomes. The 30-nm fiber forms an asymmetric, three-dimensional zigzag of nucleosomes.

What is Herterochromatin?

The highly compacted regions of chromosomes that are usually transcriptionally inactive.

What is euchromatin?

less condensed, transcriptionally active, sterically accessible form of DNA
--EUchromatin is TRUly transcribed.--

What is chromatin?

the material of which the chromosomes of organisms other than bacteria (i.e., eukaryotes) are composed. It consists of protein, RNA, and DNA.

Why does DNA condense and when does this happen?

DNA condenses before mitosis (during prophase)
The condensation of DNA makes the DNA chain copies much easier to separate from each other, because otherwise the chains would too easily get entangled into each other, thereby stopping the cell division.

What is gene expression?

the process by which DNA directs protein synthesis

What is a gene?

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

What is transcription?

The process of making RNA from DNA

Where does transcription occur in prokaryotic cell?

cytoplasm

Where does transcription occur in eukaryotic cell?

nucleus

What is a promoter?

The region of mRNA where RNA polymerase binds and starts transcription

What is a terminator?

DNA sequence that signals the end of transcription

What is pre-mRNA?

mRNA right after transcription, before splicing and processing
contains introns and exons

What are four types of RNA?

mRNA, tRNA, rRNA, snRNA

What is function of mRNA?

Messenger RNA carries copies of the genetic instructions from DNA to other parts of the cell.

What is function of tRNA?

Transfer RNA transfers each amino acid to the ribosome as it is specified by the coded messages in the mRNA.

What is function of rRNA?

rRNA molecules help hold ribosomal proteins in place and help locate the beginning and end of the mRNA message. They may also carry out the chemical reaction that joins amino acids together.

What is function of snRNA?

combines with certain proteins and is involved in RNA processing (example mRNA splicing) in eukaryotes

initiation of transcription

•Recognition step
•In bacteria (prokaryotes), sigma factor causes RNA polymerase to recognize promoter region
•Catalytic portion of RNA polymerase has similar structure in all species

Elongation of transcription

•RNA polymerase synthesizes RNA after release of sigma factor
•Open complex 10-15 base pairs long
•Template or coding strand of DNA is used for RNA synthesis
Noncoding DNA strand is not used
•Synthesized 5' to 3'
•Uracil substituted for thymine
Behind open complex, DNA rewinds

Termination of transcription

•RNA polymerase reaches termination sequence
•Causes it and newly made RNA transcript to dissociate from DNA

Capping

-Modified guanosine attached to 5' end
-Needed for mRNA to exit nucleus and bind ribosome

Tail

100-200 adenine nucleotides added to 3' end
increases stability and lifespan in cytosol
not encoded in gene sequence

Splicing

One type of eukaryotic mRNA processing in which introns are removed from the primary transcript and exons are ligated together. SPlicing of transcripts can be different in different tissues.

Describe the central dogma of biology

The hypothesis that information in cells flows in one direction, DNA codes for RNA, which codes for proteins.

What is the start codon?

AUG
defines reading frame

What is a stop codon?

UAA, UAG, UGA
When a stop codon is found in the A site, translation ends

What is translation?

the decoding of an mRNA message into a protein

initiation of translation

mRNA is attached to a subunit of the ribosome, the first codon is always AUG
requires ATP

Elongation of translation

synthesis from start codon to stop codon
aminoacyl-tRNA brings a new AA to A site, peptide bond formed
movement or translocation of the ribosome toward the 3' end of the mRNA by one codon

Termination of translation

occurs when a stop codon in the mRNA reaches the A site of the ribosome
recognized by release factors

What is the E site?

the exit site, where discharged tRNAs leave the ribosome

What is the P site?

peptidyl site- holds the tRNA that carries the growing polypeptide chain
where the first amino acid (methionine) binds because it is starting the polypeptide chain.

What is the A site?

Aminoacyl site- The site where each new tRNA delivers its amino acid.

Describe the ribosome

A structure composed of proteins and rRNA that provides the site where polypeptide synthesis occurs.
Prokaryotes have one kind of these. Eukaryotes have distinct ones in different cellular components (focus on cytosolic ribosomes).
Composed of large and small subunits.
Overall the shape is determined by rRNA.
Discrete sites for binding and polypeptide synthesis.

Where does translation occur in prokaryotic cell?

cytoplasm

Where does translation occur in eukaryotic cell?

nucleus

What is a polypeptide?

long chain of amino acids

Diploid definition

(of a cell or nucleus) containing two complete sets of chromosomes, one from each parent.

Haploid definition

having a single set of unpaired chromosomes

What is a karyotype?

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

What is a chromosome?

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

What is a chromatid?

one half of a duplicated chromosome

What is chromatin?

uncoiled DNA

What are homologous chromosomes?

paired chromosomes with genes for the same traits arranged in the same order
Two genetically similar chromosomes, one from each parent