18) Cellular Control Flashcards
What does it mean by gene expression
determine cell structure and control cell processes/
How can gene expression be controlled
transcriptional , post-transcriptional , post-transcriptional
What are transcriptional factors
Control gene expression at transcriptional level.
-Proteins bind to DNA and switch it on or off by inc or dec rate of transcription.
HOw do transcriptional factors bind in eukaryotes
bind to specific DNA sites near start of target gene
How do transcriptional factors bind in prokaryotes
Bind to operons.
What is an operon
Section of DNA that contain structural genes that are transcribed together , control elements and regulatory gene
Describe what the control elements in a operon does
Structural gene - Useful proteins ,enzymes
Promoter - Part where RNA Polymerase binds to
Operator Transcriptional factors bind to
Regulatory gene code for activator or repressor
What is the lac operon
Respire glucose , use lactose.
Produceenzymes needed tp respire lactose found on operon called lac operon.
What happens in the Lac Operon ,when lactose is not present
Regulatory gene produces the lac repressor that binds to the operator site, when no lacatose is present.
Blocks transcriptional as RNA Polymerase can’t bind to promoter
What happens in the Lac Operon when lactose is present
Lactose is present , binds to repressor, change shape so repressor can no longer bind to the Operator site.
So RNA polymerase binds to the promoter and transcription begins
What happens when mRNA is edited at the post-transcriptional level
Eukaryotic DNA contain sections that don’t code amino acids - introns.
Primary mRNA transcrips contain introns and extrons
By splicing , introns are removed
mature mRNA leaves the nucleus for translation
What is the role of cAMP
Activates proteins at post-transcriptional level
Activate proteins inside cells by altering their structure
How does cAMP activate protein
When cAMP binds to the enzyme , changes the 3D shape and release the active subunite
What is body plans
General structure of an organism
What proteins control the body plan environmenmt
Hox genes
Why are Hox Genes in all organisms helpful
Found in animals , plants and fungi .
Body plan development is controlleed in a similar way .
What are homeobox genes , why is this helpful
Highly conserved, sequences have changed very little since evolution
How does Hox genes control development
Homeobox sequences code for a part of protein called homeodomain
Homeodomain binds to specific sites on DNA - enable work as transcriptional factor
Protein bind to DNA aat start of developmental genes, activating or repressing transcription
How is Apoptosis involved in the development of body plans
Programmed cell death
Enzymes insdie cell breaj down cell components in the cytoplasm
Contents break down and break up into fragments
Engulfed by phagocytes and digested
How is Mitosis involved in the development of body plans
Differentiation create bulk of body parts and apoptosis refines unwanted structures.
What internal stimuli do genes respond to
DNA Damage
What external stimuli do genes respond to
Stress casued by lack of nutrient availabiltiy or pathogen attack
Whaat does it mean when mutations has a neutral effect
Amino acid that the triplets code for doesn’t change.
Some amino acids code for by more than one triplets
Amino acidd is chemically similar to the original
Mutated triplet codes for an amino acid not involved with the protein’s function
