36/45 EXAM 3 CH7

DNA contains what that determines most characteristics of an organism?

DNA contains what that determines most characteristics of an organism?

Sequence information

What is the function of DNA?

Information bearing molecules

What sequences code for all cellular instructions?

DNA base sequences

What are all proteins made out of?

Instructions in genes

What do proteins/genes function for?

To express and dictate physical characteristics

Before formal description what was known about DNA?

4 diff nucleotides & building blocks of large DNA mole

What did Erwin Chargaff find?

Chargaff’s rule where the complementary base pairing of A with T and G with C

What did Franklin, Gosling, and Wilkins use and what did they find?

X-ray crystallography to identify X helix shape, 34 angstrom/turn, 10 bases per turn, and Franklin deduced phosphate

Who and what determine the structure of DNA?

Chargaff’s rule and X-ray crystallography by Crick and Watson

How did the bases fit together?

Purines with pyrimidines: A to T, G to C

What is the structure of DNA

Double helix: two nucleic acid strands in spiral + rails that were the sugar/phosphate + rungs that were paired nitrogenous bases joined with hydrogen bonds

How were DNA strands complementary

Has commentary base pairing, A bonds with T, G bonds with C, one stands sequence can be determined by the other

Since DNA strands have directionality they…

Run anti-parallel to each other

What are the anti parallel directions?

One strand: 5’ to 3’ & other 3’ to 5’

When is DNA copied?

During cell division where 1 parent cell becomes 2 daughter cells

What is the mechanism of DNA replication?

Each stand is used as a template to build 2 half new DNA molecules

What happens during cell division?

DNA strands are split apart, the old strands serve as template for DNA building enzyme (DNA polymerase), and then DNA polymerase adds complementary bases as it moves and reads the strands

What is DNA polymerase?

DNA building enzyme that reads old strands to add complementary bases

What is the genome?

All native DNA inside of cell

How does the genome fit into the cells nucleus?

DNA is wrapped around histone proteins

What are histones?

Histones coil into highly compact structure called chromosomes

What type of chromosome do prokaryotes have?

Single circular chromosome in nucleoid region

What chromosome do eukaryotic have?

Multiple linear chromosomes in the nucleus

What is a karyotype

Chart showing all chromosomes from an organism.

How many chromosome pairs do humans have?

23 pairs and 46 total chromosomes

what do pairs 1-22 of a human karyotype known as?

Autosomes

What are autosomes?

Genetic instruction of general life processes (metabolic)

What is pair 23 of a human karyotype ?

Sex chromosomes to determine biological sex of a person

What is a females sex chromosomes?

XX

What is a males sex chromosomes?

XY

What is a gene?

Segment of DNA w instructions to make functional RNA/protein

In sexually reproducing eukaryotes what do chromosomes come in?

Homologous chromosomes

What are homologous chromosomes?

Contain same gene order down linear DNA

What are the different forms of genes called?

Alleles

What is the central dogma?

Describe the flow of information from DNA to RNA to PROTEIN

What are the two phases of central dogma

Translation and transcription

Where does transcription take place?

In nucleus!!!

Where does translation take place?

In cytoplasm

What is transcription?

Using DNA as template to synthesize RNA.

What are the 3 different steps of transcription?

Initiation, elongation, and termination

What is initiation in transcription

We have promoter region acts as signal and gene starts and knows what stand to use as template + RNA polymerase used to bind to template strand

What is elongation in transC?

RNA poly moves and adds complementary bases to gene chain

What is termination in transC?

Termination sequence=end of the gene. RNA poly reads termination sequence and releases from DNA & mRNA molecule released

What must be processed from preRNA into mature mRNA before leaving nucleus?

mRNA

What is mRNA splicing?

Segments of RNA are removed & remaining segments are joined/ together

What are introns?

Segments removed from from pre-mRNA=trash RNA

What are exons?

Segments joined together to make mature mRNA

What preforms translation

Ribosomes

What happens in translation?

Translation converts mRNA code into polypeptide proteins

What does the ribosome read in translation?

3 CODON BASES AT A TIME

what is tRNA in transL?

transfer rna that Carrie’s specific AA’s to ribosome

What are the 3 steps of translation in cytoplasm?

Initiation, elongation, and termination

What is initiation in transL?

Ribo scans for start codon AUG to incorporate AA Met

What is terminatiom step in transL?

Has stop codons to stop proteins & causes ribosomes to release from mRNA

What are polysomes?

Multiple ribosomes in a single mRNA & increases protein production

How do cells regulate gene expression?

Cells evolved ways to control what genes are expressed to save energy and resources

How does gene expression look in prokaryotes ?

Bacteria can turn genes on or off.

What is lac operon?

A group of genes that break down lactose sugar lactase

What do operons contain

Promoter, operator, and operon genes

What is the promoter?

site where rna poly binds and recruits RNA

What is the operator?

DNA sequence that is a regulatory region

What do operon genes do?

Code the required proteins?

What if there is no lactose present?

Repressor proteins binds to the operator and block RNA polymerase & operon gene expression

What if there is lactose present?

Lactose will bind to the repressor & falls off which leaves the polymerase to transcribe genes in operon

What are the 6 mechanisms for gene expression regulation in eukaryotes?

DNA availability, transcription factor availability, mRNA processing, mRNA transport from nucleus, RNA degradation, and protein processing/degradation

What increases the functional outcomes of proteins in an organism?

Post transitional modifications where proteins are modified after translational and can have different functions than other proteins that have the same genome

What besides post transitional modifications increase total number of cell types?

Alternative splicing

Number of genes in a genome underestimates the total number of ….

Proteins in the proteome

What are mutations?

Unintended changes in the cells DNA sequence

What can mutations affect?

A single DNA base, few bases, or large portion of chromosomes

What are small scale mutations?

Includes frame shift mutations, silent mutations, point mutation, & substitution mutation

What is frameshift mutation?

Includes frame shift mutations that have the insertion is deletion in a resting frame for a protein.

What are silent mutations?

Point mutations that do not change the proteins AA sequence.

What tolerates mutations in the third base causing WOBBLE effect of codon?

Genetic code redundancy

What are large scale chromosome mutations?

Deletion, duplication, inversion, translocation, insertion

What is a spontaneous point mutation during cell division?

Where DNA polymerase adds the wrong base when copying DNA.

What has proofreading ability to check each new nucleotide against the template

DNA polymerase

What can be permanent if not corrected With replication repair mechanism during cell division?

DNA point substitution mutation

What are mutagens?

External agents that induces mutations these cause a bulge in DNA ladder

What are examples of mutagens

Radiation, chemicals, and infectious agent

What are viruses?

Very small protein shells that contain genetic material of DNA/RNA. Attacks red blood cells

What is the function of a virus?

survive and replicate more of itself and infect new hosts

What are the five stages of viral replication?

APSAR. Attachment, penetration, synthesis, assembly, and release

What is the synthesis step for viral rep?

Host cell hijacked to produce copies of viral genome/proteins by using all their resources ATP, ribosome, AA, enzymes, etc

What is the assembly stage of viral rep?

Viral particles assemble abs genetic info moves inside

What is the release stage of viral rep?

Host cell releases newly formed viral particles.

Some viruses kill host cell during release which is known as

Lysis

Other host cells are released via..

Exocytosis/vesicles

What are the 2 potential lifecycle phases?

Lytic & lysogenic phase

What is the lytic phase?

Rapid viral replication which causes infected cells to die & there is a massive release of new viral particles into org/environment

What is the lysogenic phase?

Phage viral genome incorporated into host genome.

In lysogenic phase, viral genome maintained within host until…

A stressful condition trigger entry into lytic phase

In animal hosts the lysogenic phase is called this

LATENT. Example is herpes where latent herpes virus transitions into lytic phase

What are the two ways to combat viruses?

Supportive therapy & wait for immune system to recognize the virus & develop immune response or vaccines to train immune state to recognize pathogen before infection occurs.

What are prions?

Protein based infectious particles.

What happens for prions to form?

Midfielder proteins cause other proteins to misfold & results in massive accumulation of zombie proteins.