Lecture 22 - FoB

DNA replication only occurs in cells in _ phase before mitosis and meiosis.

S

How often is protein synthesis taking place occur and in what cells?

protein synthesis occurs almost all the time in almost all cells

What is the purpose of DNA?

holds the information to make proteins (proteins determine a lot about a cell look and function)

are proteins specific or non-specific?

proteins are very specified

what is a genome? how does it related t

an organelle’s complete set of genetic instructions made of DNA

• differentiation comes from different parts of the genome

what is the purpose of mRNA?

information carrier

• carries genetic instructions from DNA in a cell's nucleus to the ribosomes in the cytoplasm, where the cell builds proteins

is there a little or a lot of genetic data?

as the cost of sequencing decreases, the amount of genetic data has increased

what happens at the arrow?

1. genome → epigenome

2. epigenome → transcriptome

3. transcriptome → proteome

4. proteome → metabolome

1. transcription

2. expression

3. translation

4. function

a ____ on a chromosome encodes a ______

gene, encodes

what are the monomers of proteins and nucleic acids?

Nucleic acids: nucleotides (info from DNA to make proteins)

proteins: amino acids (later create a functional protein)

define the arrows:

DNA (info storage) → mRNA (info carrier) → proteins (active cell machinery)

arrow 1: transcription

arrow 2: translation

what is RNA? Sugar? Bases? Stranded (1 or 2)? Functions?

RNA: mediates protein synthesis during transcription and translation

sugar: extra OH- group (ribose sugar)

bases: Adenine binds with Uracil

stranded: single-stranded

function: carriers protein encoding information

What are the 4 steps of transcription?

1. initiation

2. elongation

3. termination

4. processing

What is the purpose of transcription?

mRNA “copies” of genes are made by RNA polymerase

define protein complexes responsible for packing DNA

what makes up chromatin?

1. histones

2. DNA + histones

What determines if the DNA state is “open” or “closed”?

What is euchromatin or heterochromatin?

1. histones

euchromatin: actively transcribed region of DNA; open

heterochromatin: not actively transcribed; closed

define: proteins that bind to DNA and regulate gene expression (gene control) and 2 examples

where do these bind?

Transcription factors (TF): proteins that bind to DNA and determine how much or if a gene is expressed

bind way upstream to enhancers or silencers

activators: promote transcription

repressors: stop transcription

define: proteins that bind to DNA and determine if gene expression is turned on

where do these bind?

general transcription factors

bind to the core promoter region - TATA box

what determines the start of transcription?

the promoter

what is the TATA box?

a DNA sequence

how does the process happen with the promoter, TATA box, and GTF?

open cromatin →

The promoter contains the TATA box →

GTFs bind to the promoter → (

dumb) RNA polymerase is called over by the GTFs (bat signal) →

Transcription begins →

RNA made

what is different about the making of RNA process than in DNA?

RNA polymerase does not need a 3’ OH group, or primer

RNA is made as needed when genes are expressed and from a specific gene

RNA only one strand is copied

A binds to U instead of T (uses uracil)

RNA nucleotide building blocks (not DNA)

what is read by RNA polymerase and what direction is mRNA built?

reads DNA 3’→ 5’ direction

builds mRNA in the 5’ → 3’ direction (antiparallel to the template strand with complementary bases)

no primer needed

what is the step that means elongation has started?

as soon as RNA codes for 1st mRNA nucleotides, we have entered elongation

what is the difference in the lower and upper case in the elongation process?

the lower case represents the promoter region, upper case is the beginning of the template

what strand does RNA polymerase use?

template strand

what determines where the RNA polymerase starts and stops?

nucleotide sequences

what is the purpose of a transcription termination?

RNA polymerase will encounter the termination sequence encoded in the DNA (a specific series of base pairs)

RNA polymerase falls off DNA and releases the mRNA transcript

processing: is mRNA modified before it leaves the nucleus?

yes

how does splicing happen? what protein is at play here?

to remove noncoding sections called introns from pre-RNA and connect the coding sections called exons to make the mature DNA

snRNP proteins bind to specific DNA sequences to mark exon boundaries for removal

(happens in eukaryotes before the mRNA leaves the nucleus and is translated into a protein)

what happens to introns?

they stay within the nucleus

what is the purpose of splicing?

protein variation - can get multiple protein variations from 1 gene (discredits the 1 gene-1 protein hypothesis)

What is the process of capping and tailing? What is the purpose?

5’ end of the strand gets a cap (5’ methalG cap)

3’ side gets a string of adenine nucleotides added to it (3’ PolyA tail)

purpose: stabilize mRNA transcript + helpful for translation machinery

after the mRNA leaves the _____ and goes into the ______ it is considered mature mRNA

nucleus, cytoplasm

Spliceosomes are composed of _____. (2)

small RNAs and proteins

what is the minimal genetic code #? what is the benefit to having many codons?

21 codons

having more than the minimum number of codons is error tolerance. Because of the redundancy in an expanded code, not every base pair change will change the meaning of a codon