AP Bio: Unit 6- Gene expression and regulation

DNA Helicase

enzyme that unwinds the double helix structure of DNA by breaking hydrogen bonds between complementary base pairs

ligase

glues DNA fragments together

Topoisomerase

keeps DNA from supercoiling

SSBP (+ what does it stand for?)

Single stranded binding protein, binds to DNA strands to keep them separated

DNA polymerase I

replaces RNA primers and leaves gaps between okazaki fragments, and replaces gaps with the correct nucleosides

DNA polymerase III

synthesizes new strands during DNA replication

Primase

makes rna primers that tells DNA polymerase where to start building

Leading strand runs…

5’ to 3’

Lagging strand runs…

3’ to 5’

Polymerase adds DNA on the … end of a growing strand

3’

New DNA strands are built in what direction

5’ to 3’

Okazaki fragments

Short sequences of DNA nucleotides synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication.

Telomeres

a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes

Telomerase

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

Replication fork/replication bubble

space that forms during DNA replication

Origin of replication

a specific sequence in the DNA where replication begins

How to count carbons on a sugar

numbered right after the oxygen in a clockwise direction

Bidirectional synthesis

DNA replication happens in both directions

how many origin sites in eukaryotes

hundreds/thousands of origin sites per chromosome

RNA grows in the … to …. direction

5’ to 3’

Activator

a protein that binds to specific DNA sequences called enhancers, which are located near the promoter region of a gene. By binding to the enhancer, the activator helps initiate and increase the transcription of the gene.

Codon

sequences of three nucleotides in DNA or RNA that correspond to specific amino acids or stop signals during protein synthesis.

enhancers

sequences of DNA that increase the likelihood of transcription by providing binding sites for proteins known as transcription factors.

Exons

the sections of DNA that are transcribed into mRNA and then translated into proteins. They contain the actual genetic information coding for protein synthesis.

Introns

non-coding sequences within genes that are removed during RNA processing, while exons are coding sequences that remain in the mature mRNA and code for proteins.

Ribosomes the central dogma of biology

made of both protein and rRNA, performs protein synthesis

RNA polymerase

enzyme that synthesizes RNA from DNA during transcription

spliceosome

complex assembly of RNA and protein molecules that removes introns from pre-mRNA during splicing.

transcription factors

proteins involved in the process of converting, or transcribing, DNA into RNA. They help regulate gene expression by binding to specific sites on DNA and controlling how often genes get transcribed into mRNA molecules.

Transcription

the process of copying out the DNA sequence of a gene in the similar alphabet of RNA. The first step of gene expression

Stages of transcription

1. initiation

2. elongation

3. termination

Initiation (transcription)

RNA polymerase binds to a sequence of DNA called the promoter, found near the beginning of a gene. Once bound, RNA polymerase separates the DNA strands, providing the single-stranded template needed for transcription.

Does every gene have its own promotor region

yes

Elongation (transcription)

RNA polymerase builds mRNA out of complementary nucleotides, making a chain that grows from 5' to 3'

Termination (transcription)

Sequences called terminators signal that the RNA transcript is complete. Once they are transcribed, they cause the transcript to be released from the RNA polymerase.

Terminators

Specific sequences in the DNA molecule that signal the end of transcription. They tell RNA polymerase when it's time to stop adding nucleotides to the growing mRNA strand. Causes mRNA to be released from RNA polymerase

RNA processing

4 main things that happen in RNA processing

• introns are removed

• exons are joined together

• add 5’methyl caps

• add poly-A tails

stages of translation

1. initiation

2. elongation

3. termination

“ingredients for translation”

• tRNA

• ribosome

• mRNA