Exam 3 Flashcards
What are constitutive genes?
These are housekeeping genes and they are NOT differentially regulated, meaning they are active all the time and they ALWAYS need to be expressed in order for the cell to be alive; example: metabolism genes.
difference between housekeeping genes and specific genes.
Housekeeping genes present in all tissue types – regulate processes that all cells need (think metabolism). Specific genes are specific to their tissue type
When does the majority of gene regulation take place?
Transcription
What is an operon?
An operon is a cluster of genes that are transcribed and translated together with one promoter; only prokaryotes have them
Why are operons helpful
Because prokaryotes do not want to waste all their energy transcribing genes that they do not need to have on ALL the time so they have operons that regulate it.
What repressible operon did we learn about?
Trp operon
What is a repressor?
Binds to the operator of the operon to prevent the transcription of the genes
What is the corepressor in the trp operon?
Tryptophan
If there is tryptophan present in the cell, is the gene for tryptophan being transcribed?
No, because there is tryptophan (corepressor) that binds to the repressor and causes a shape change to activate it to bind to the operator therefore hindering transcription
What inducible operon did we learn about?
The lac operon codes for genes that make the enzymes needed to metabolize lactose a type of sugar. when the inducer binds to the repressor, the repressor is removed which allows the cell to transcribe the genes needed to make the proteins that can digest lactose.
What is the inducer in the lactose example?
Allolactose
Is the repressor normally on or off? (in lac example)
On
If there is glucose absent and lactose present is the lac operon on or off?
On
If there is glucose present and lactose present is the lac operon on or off?
Off
What type of gene regulation are operons?
Transcription
What is gene imprinting:
a process in genome modification where some genes are shut down (methylated)
What impact does DNA methylation have on transcription?
Methylation will tighten the DNA onto the histone inhibiting transcription
What impact does DNA acetylation have on transcription?
Acetylation will loosen the DNA and make transcription more likely
What are the two regulatory transcription factors?
Activators and Repressors
Activators and repressors;
activators enhance and repressors silence
Alternative splicing
*Allows for there to be many genes encoded in one transcript
*By changing what exons are included in the mRNA transcript it can change what genes are expressed and also maximize the number of genes included in one transcript
Constitutive exons:
exons always included and in the order in which they appear on the pre mRNA
Eurkaryotes
Alternative exons;
sometimes are included but other times are not always included
Eukaryotes
what is the advantage of alternative splicing
we can produce tissue specific proteins and developmental specific versions of proteins
What is quorum sensing
*Quorum sensing is the ability for bacteria to communicate with each other for the purpose of producing something; it is a way for them to alter gene expression
*The bacteria are always producing signals but once the concentration of them is high enough they will alter gene expression for the purpose of producing something
what three things can a bacteria do if it is able to communicate with other bacteria?
They can produce biofilms, toxins, and spores, exchange genetic data
What stage in the cell cycle does quorum sensing occur and therefore the things that are produced via quorum sensing?
Stationary
Examples of biofilms in real life.
Teeth, growth in catheters, growth in pipes can cause chronic infection
Why do people with diabetes usually have trouble with their feet?
Biofilms protect from antibiotics.
But the antibiotics already have a hard time circulating to the feet so the biofilm provides an extra layer therefore prolonging the infection
endotoxins
*not actively secreted and have general symptoms of fever, lethargy, malaise; produced by the LPS of gram negative bacteria
*large doses can cause hemorrhagic shock and tissue necrosis
PRODUCED BY LIPID POLYSACCHARIDES OF GRAM-
Exotoxins
secreted and have very specific targets
AB toxins;
two component exotoxins where the A component is the active toxin and the B component helps the toxin to bind to the target cell
Photoautotroph;
energy from the sun and makes its own C-C bonds
Photoheterotroph;
energy from the sun and ingests pre existing C-C bonds
Chemoautotroph;
energy from chemical bonds and makes its own C-C bonds
Chemoheterotroph;
energy from chemical bonds and ingests pre existing C-C bonds
lithotrophy
Ability to use inorganic molecules to generate energy and build cells; many are chemoautotrophs
example of lithotrophy w nitrogen cycle
ammonia oxidizers which use ammonia as a source of energy and they are critical for the nitrogen cycle to progress by oxidizing ammonia
Relationship between bacteria and root nodules.
All living things need lots of nitrogen but the only organisms that can fix it are bacteria and archaea; so plants (eukaryotes) have a mutualistic relationship with bacteria and archaea;
What type of process is nitrogen fixation
anaerobic respiration
2 plant systems
Shoot system, root system
What is the function of roots? Why do roots have root hairs?
Anchor the plant, absorb nutrients and water, store carbohydrates
What is the difference between a taproot and a fibrous root?
Taproot: one large vertical root, many small lateral branches
Fibrous: mat of slender roots spreading out
Explain the three components of a stem.
Nodes, internodes, buds
hat is the purpose of a plant having modified stems, leaves, or roots?
It helps them better adapt and survive in the particular environment they are in.
Dermal tissue
Skin of plant
Vascular tissue (plants)
transports materials between roots and shoots
Xylem:
*transports water (vascular)
*Tracheids & Vessel elements
*dead at maturity
Phloem:
*sugars transportation (vascular)
*Tube shaped living cells
*Sieve tube elements
*Companion cells
*Alive at maturity
Ground tissue
bulk of plant tissue, can function in storage, photosynthesis, etc
Parenchyma
(photosynthetic storage cells)
Ground tissue
alive at maturity
Collenchyma
(support growth in young plants and shoots, alive at maturity)
Ground tissue
Sclerenchyma
(support and strength, dead at maturity)
Ground tissue
two types of meristems
Apical (primary growth, length of shoots and roots)
lateral (secondary growth, increase thickness of stem in woody plants)
what are meristems
sites of active cell division
What are two ways plants respond to stimuli?
Adjust their growth, adjust their development
what occurs when light is detected by phytochromes.
*Produces cGMP which phosphorylates a protein kinase. This travels to the nucleus and phosphorylates and certain transcription factor.
*Opens a calcium ion channel which phosphorylates a protein kinase. This travels to the nucleus and phosphorylates a certain transcription factor.
*Both transcription factors initiate the transcription and translation of proteins required for the de-etiolation response.
de-etiolation.
*he greening response; stem elongation slows, leaves develop, there are many chloroplasts/chlorophyll, extensive root development for water absorption.
*Allows them to maximize photosynthesis.
Auxin Purpose
Stem elongation, enhances apical dominance, the tropisms
Auxin location
Shoot apical meristems and young leaves
Giberellins Location
Meristems of apical buds and roots
Ethylene Location
Produced by most parts of plant
Giberellins Function
Stem elongation, seed germination
Ethylene Function
Ripening of fruit, triple response
Cytokinins Location
Roots
Cytokinins Function
Cell division in shoots and roots, modify apical dominance
Abscisic acid Function
Inhibits growth, stomatal closure and seed dormancy
Abscisic acid Location
All over the plant (detected in all organs and living tissues)
Hormone involved in phototropism?
Auxin
gravitropism.
The growth of roots and shoots toward or away from the direction of gravity
Auxin
apical dominance
Terminal bud’s ability to suppress development of axillary buds
Cytokinin and mostly Auxin
Cut top to encourage lateral growth
seed germination
Water diffuses into the seed and this triggers GA to be released which triggers alpha amylase. This converts starch in the cell wall to sugars that can be used by the growing seed.
Giberellins
triple response
A plant’s response to mechanical stress; slower stem elongation, thickening of the stem, curvature to horizontal growth
Ethylene
feedback mechanism of fruit ripening
positive feedback mechanism. Ethylene causes ripening, which in turn stimulates more ethylene production.
conditions that would cause the stomata of a plant to be closed and how this occurs.
ABA causes potassium channels in the plasma membrane of guard cells to open → potassium ions diffuse out → water flows out osmotically → guard cell pressure decreases and this leads to the closing of stomatal pores.
How do plants tackle the problem of the soil’s general charge?
Acidify the soil by releasing CO2
How does acidifying the soil assist in mineral absorption?
With the soil more acidic, the strong negative charge is gone and mineral cations are released.
Which vascular tissue do water and minerals try to get to? What are the transport cells associated with this tissue?
Xylem, tracheids and vessel elements
What is the Casparian strip and its function?
A waxy strip in the cell wall of endodermal cells (make up the boundary of vascular tissue) which makes endodermal cells impervious to water. Forces water to take the symplastic route through the cell.
Explain bulk flow. Is it sufficient to explain xylem transport?
The active pumping of water and minerals into the xylem causes positive pressure which forces particles up the xylem
it is not sufficient
cohesion-tension hypothesis.
water is transported even though bulk flow is insufficient to cause it all.
Water is lost at the leaves through stomata which creates negative pressure at the top of the plant.
Due to hydrogen bonding, the entire column of water is “pulled” up.
What is transported in the phloem? What are its transport cells?
Sugar, sieve tube elements
Where is sucrose transported to and from?
produced in mesophyll cells
produced to sieve tube elements where it can access phloem via apoplastic or symplastic route
How is sucrose transported into the cell? Does this require ATP?
Actively transported into the cell, YES
phloem transport requires a chemiosmotic mechanism, explain
ATP is used to pump H+ proteins from low to high concentration, when H+ flows down its concentration gradient it produces sufficient energy that sucrose is able to be actively transported into the cell
Is there a high or low concentration of sugar near the source (leaf)?
There is a high concentration near the source
What direction is bulk flow driven in?
Away from the source
When sugar needs to be used or stored, how is it transported out of the phloem?
Passively diffuses out of phloem into sink cell
What is the metabolism of animals?
Chemoheterotroph
What are the four types of animal tissues?
Muscular, epithelial, nervous, connective
epithelial tissues
Cover the outside of the body and lines the organs and cavities; the cells are closely packers and the basement membrane is present where it is classified based on cell shape and layers
connective tissues
These are cells embedded in an extracellular matrix
types of connective tissue
Collagen - building block of skin/bone
Mineral matrix– bone
Liquid matrix– blood
Functions of connective tissue
Form structure
Protection
Bind and connect
nervous tissue.
Receives processes and transmits information
what makes up nervous system
Nervous system consists of neurons and glial cells
How does the way that we exchange materials with the environment differ from an amoeba?
We require systems in order to exchange our materials with the environment while the amoeba is thin enough that every cell is 0-1 cells away from the environment and can therefore utilize diffusion to do so
What two systems play a prominent and integral role in maintaining homeostasis?
Nervous and endocrine
regulator.
Control mechanism maintain internal conditions
conformer.
Allows internal conditions to vary with environment
what is shuttling? Is this a behavioral or physiological control mechanism?
Going back and forth from shaded areas to not shaded areas, behavioral
negative feedback? Is this a behavioral or physiological control mechanism?
Where the secreted molecule or signal inhibits the molecule that secreted it, physiological
Thermo regulation
If the body temperature rises: hypothalamus activates cooling mechanisms → blood vessels dilate and we sweat
If the body temperature lowers: hypothalamus activates warming mechanisms → blood vessels constrict and we shiver
What organisms’ body temperature is determined by internal metabolism? By external environment?
Internal: endotherm
External: ectotherm
What organisms’ body temperature is constant regardless of the external temperature? Which fluctuates?
Constant: homeotherm (mammals)
Fluctuates: poikilotherm
