USE FOR 18 (13.4) Flashcards
Bacteria and other prokaryotes need to transcribe all of their genes at the same time (True or False)
false
what is regulating gene expression
only using genes necessary for the cell to function
enzyme activity regulation aka
feedback inhibition
DNA binding proteins in prokaryotes regulate genes by controlling
transcription
enzyme activity regulation
when theres too much product being produced by a certain enzyme or chain of enzymes, the product will go back and bind to the (inhibit) first enzyme in the metabloc pathway in order to not waste stuff
Operon
a group of genes that are regulated together (genes usually have related functions) made of promoter, operator, and the genes being transcribed
Promoter
site where RNA-polymerase can bind to begin transcription
Operator
DNA binding site of repressor protein
What is the first step of turning the operon on
When lactose is added, it diffuses through the cell and attaches to the lac repressor which causes the repressor protein to change shape and fall off the operator
What is the second step of turning the operon on
RNA Polymerase bind to promoter and transcribes the genes of the operon
Most eukaryotic genes are controlled
individually and have more complex regulatory sequences
TATA box
short region of DNA that is located about 20 - 30 base pairs away from the start gene containing the sequence TATATA…. or TATAAAAA….
what is the function of the TATA box
binds a protein that helps position RNA polymerase by marking a point just before the beginning of a gene
Transcription factors
DNA binding proteins that control the expression of genes
In most cases, what must happen before RNA polymerase is able to attach to the promoter region and start transcription
multiple transcription factors must bind
Some factors can affect multiple genes at once (True or False )
True
Receptor complexes
Made of receptor proteins and chemical messengers etc
Receptor complexes can act as a transcription factor that binds to DNA and sends out a chemical signal that can
activate multiple genes
What other factors can affect gene expression
- exit of the mRNA
- stability of mRNA
- breakdown of gene’s protein products
Cell specialization =
complex gene regulation
cells contain lots of…
small RNA that is not mRNA, tRNA, or rRNA
the small mRNA affects
gene expression
Dicer
enzyme that cuts the double stranded loops of mRNA into miRNA
miRNA stands for
micro RNA
How are silencing complexs created?
after the mRNA is split, the two strands of the loop separate and form miRNA —> the miRNA sticks to some mRNA molecules and stops them from passing on their protein making instructions
RNA interference
blocking gene expression by means of miRNA silencing
does RNA interference take place in all organisms?
yes and it plays a role in human growth and development
RNAi technology holds the promise of
medical scientists being able to turn off the expression of virus cells or cancer cells
differentiation
becoming specialized in structure and function
homeotic genes
regulate organs and their development
homeobox genes
Code for transcription factors that activate other genes important in cells development and differentiation
determines the presence of body parts
Hox genes
they tell the cells of the body how to differentiate as the body grows and determines the location of body parts
Why do common factors of genetic control exist?
because all these genes have descended from the genes of common ancestors
What environmental factors can affect prokaryotes and eukaryotes
temperature, salinity, nutrient availability
metamorphosis can be an example of how
environmental influences affect gene expression
operators are aka
o region
When is the lac repressor on the operator
the lac repressor is ALWAYS on the operator unless it is bonded to lactose
In lac operon, lactose is known as the
inducer
the TATA box is a part of the
promoter
How do environmental factors affect metamorphosis
Lack of nutrients, drying of ponds, amounts of food
what is the function of the TATA box
binds a protein which helps position RNA polymerase right before the beginning of a gene
enhancer
short sequences that recruit activator proteins which help RNA Polymerase work efficiently
is the enhancer a part of the promoter region
no
What are some examples of transcription factors
attracting RNA Polymerase, opening up chromatin, and blocking access to certain genes
Promoters have ______ binding sites for transcription factors
multiple
Cell specialization requires
genetic specialization
homeotic genes are also known as
master control genes
how long are hox genes
180 bps
how are hox genes arranged
from head to tail
Mutagens
Chemical or physical agents in the environment that cause mutations generally these are not good or bad
examples of mutagens
uv radiation, smoke, infectious agents, rays, etc.
gene expression regulation
instead of blocking enzyme function, block transcription of genes for all enzymes in metablic pathways in order to save energy
what type of cell does gene expression regulation
only prokaryotes
transcription unit
the genes that are grouped together
how many main types of operons are there and what are they
2 –> negative and positive control
how do inducible operons work
there’s an operon that’s off bc there’s a repressor bound to the operator so in order to turn the operon on, there’s an inducer molecule that changes the shape of the repressor so it cnt bind to the operator and the polymerase can go and waboosh
what are the the types of negative gene regulation
repressible operon and inducible operon
how do repressible operons work
so the operon is on bc there’s nothing bound to the operator and so the translation is like translationing and basically when there’s too much shiz being made by the proteins and wtv there’s an inactive repressor protein that becomes active when the product binds to it and then it binds to the operator and stops the production bc its wasting resources bc there’s too much and its like not needed
how does positive control of a gene
so basically there’s nothing on the operon and then there’s a signal protein that binds to an inactive activator protein which makes it active and then this protein+signal thing binds to before the promoter and its like HEY RNA POLYMERASE COME DO UR SHIIIIIIIIIIII
what type of pathways are repressible operons for
anabolic
what type of pathways are inducible operons for
inducible
