Exam 1(post ME 1) Flashcards
Why are prokaryotic cells typically smaller than eukaryotic cells?
Prokaryotic cells move molecules through diffusion which is limited by inner and outer environment concentrations reaching equilibrium
Nuclear membrane
Inner and outer layers, made of lipid bilayer, outer later is connected to ER
Vesicles
Move along microtubule tracts from ER to golgi
Transcription location
nucleus
Function of smooth ER
lipid synthesis
ER lumen
space in ER
Where does translation occur?
cytoplasm
Characteristic of protein that need to pass through membranes
nonpolar
soluble proteins
synthesized in cytoplasm
Difference between membrane embedded protein synthesis and secreted protein synthesis
Embedded proteins have 2 signal sequences where transport stops
cis vs trans golgi
Cis is the receiving side and trans in the shipping side
How is the cell membrane built/repaired?
Vesicles carry phospholipids, lipids and protrin to make it bigger and take damaged phospholipids away
Which cells have mitchondria?
all eukaryotes
semiautonomous organelles
- mitochondria, chloroplasts, plastids
- reproduce/divide themselves
- depend on cell for some proteins
- could not survive on their own
- originated from endsymbiosis
Where did mitochondria originate from?
Oxygen using, nonphotosynthetic prokaryotes
Where did chloroplasts come from?
Photosynthetic prokaryotes
Structure of mitochondria
- inner and outer membrane: inner membrane folds to increase surface area to make more ATP
- inter membrane space between inner and outer membrane
- Matrix: innermost, soluble portion of mitochondria, analogous to cytosol
- ribosomes
Chloroplast structure
- 3 membranes: inner, outer, and thylakoid membrane
- Thylakoids are stacked, green and connected
- Inter-membrane space between inner and outer membrane
- Stroma: inner, soluble portion of chloroplast
- ribosomes
Characteristics of multicellularity
- Organisms consist of more than one cell
- Cells adhere to and recognize one another
- Cell specialize and tissues form
Do all plants and animals have tissues?
All animals except sponges, and all plants have a certain type
Cytoskeleton
- Internal structure of the cell
- dynamic
- made of microtubules and filaments
- all cells have a cytoskeleton, it is more complex in eukaryotes
Microtubules
- part of cytoskeleton
- Hollow tubes made of tubulin and dimers
- largest cytoskeleton component
- cell shape, motility, chromosome movement in division, organelle movement
- control flagellum
Microfilaments
- Two intertwined strands of actin filaments
- aka actin filaments
- smallest part of cytoskeleton
- cell shape, muscle contraction, cell motility, division of animal cells, cytoplasmic streaming in plant cells
- Muscle contraction
Intermediate filaments
- medium sized filaments in cytoskeleton
- made of several different proteins
- coiled protein structure
- cell shape, anchorage of nucleus and other organelles, formation of nuclear lamina
Extracellular matrix
(ECM) •outside the cell •gives strength, structural support and organization •important in cell signaling •built by endomembrane system •proteins are embedded in cell membrane
Adhesive proteins
Proteins in the ECM
•Fibronectin: connects cells to EVM
•Laminin: connects cells to ECM in basal lamina
Structural ECM proteins
- Collagen: large fibers, many types, strength
2. Elastin: elastic fibers in ECM
Basal lamina
base layer that cells stick to
Animal cell attachment
- Tight junctions: hold cells together, nothing passes between cells, stitching pattern, different proteins than desmosomes
- Gap junction: allows small molecules and ions to flow between cells
- Desmosome: Parts of cytoskeleton are attached, gives tissues strength, keeps cells together, protein-protein interaction, no passing through
Plant cell attachment
- Middle lamella: Sugary, sticky, glue like substance secreted by plant cells that holds cells together
- Plasmodesmata: Leaves gaps, tubes that penetrate two cells holding them together, substances can travel through the tubes
Attachment in bacteria
They fibriae, and a pilus/pilii
How do vesicles move within cells?
Motor proteins “walk” vesicles along microtubules, powered by hydrolyzing ATP
What happens when ATP is hydrolyzed?
A phosphate group is removed, and it becomes ADP
Microtubule organizing centers
Basal bodies and centrioles
How are cilia and flagellum moved?
They are controlled by microtubules in doublets, attached by motor proteins.
Centrioles
microtubule organizing centers that also organize spindle fibers for mitosis in eukaryotes
How are cilia and flagella attached to the cell?
the are extensions of the cell that are completely enclosed by cell membranes
Genome
all of the DNA in a cell
Proteome
proteins found in a specific type of cell
Which cells in the human body have different genomes?
red blood cells have different genomes from the rest of the body
Differentiation
When stem cells turn into a specific cell type as a result of external signals. This process is irreversible
What are most cell signals?
chemical signals
What level of variety is found in cell signaling across all domains of life?
There is some variety, but overall similar
Steps of cell signaling
- Reception
- Transduction
- Response
How do bacteria search for food?
They “run and tumble”. The swim in a direction, then let their flagella spread out. This process is repeated until food/signals are found
How does transduction work?
When a signal is received, the receptor changes shape on the inside of the cell, causing further downstream changes
What is true of all signal receptors?
- the signal is specific
- bind of signal causes shape change to receptor
- most signal receptors are plasma membrane proteins
Steroid receptors
- Cell signal receptors inside the cell
- Go into nucleus after signal binding
- acts as a transcription factor
Transcription factors
something that interacts directly with DNA
G protein-coupled receptor process
- Signaling molecule binds to G protein-coupled receptor
- G-protein detaches from G protein-coupled receptor and travels to inactive enzyme, this is powered by hydrolysis of ATP
- Inactive enzyme is activated when G protein attaches to it
- G-protein heads back to G-protein coupled receptor
Types of metabolism
Catabolic: breaks molecules down via hydrolysis, releases energy, cellular respiration
Anabolic: Builds molecules via dehydration, consumes energy, protein synthesis, photosynthesis
First law of thermodynamics
Conservation of energy, energy can not be created or destroyed
Second law of thermodynamics
Every energy transfer increases entropy of the universe, aka heat is lost in every reaction
free energy
energy that can do work when pressure and temp are uniform(🔼G)
What do high and low levels of free energy indicate
High: less stable, greater work capacity
Low: More stable, less work capacity
Exergonic/endergonic reactions
Exergonic: net release of free energy(🔼G<0), spontaneous, catabolic
Endergonic: Absorbs free energy from surroundings, not spontaneous, (🔼G>0), anabolic,
ATP components and name
Name: Adenosine triphosphate
Components: ribose, adenine(a nitrogenous base), and 3 phosphate groups
ATP hydrolysis
Terminal P from P tail is removed, energy comes from moving to a state of lower free energy
How does ATP power the cell?
Coupling endergonic and exergonic reactions
Types of work a cell does
- Chemical
- Transport
- Mechanical
How can reactions be coupled in metabolic pathways?
Energy from an exergonic reaction can be used as activation energy for an endergonic reaction
How is ATP recycled
ADP can be made back into ATP
How do enzymes speed up reactions?
The decrease the activation energy of a reaction by
- orienting substrates correctly
- straining substrate bonds
- providing a favorable microenvironment
- covalently bonding to the substrate
Active site
Region of the enzyme where the substate fits
Things that change the shape of an enzyme
- Cofactors: inorganic
2. Coenzymes: organic
Competitive vs noncompetitive inhibitors
Competitive: bind to active site of enzyme, competing with substrate
Noncompetitive: bind to a part of the enzyme other than the active site, causing the enzyme to change shape, making the active site less effective
Allosteric activator/inhibitor
Changes shape or stability of the enzyme by binding to a location on the enzyme other than the active site
feedback inhibition
When the end product of a metabolic pathway inhibits enzymes of the initial substrate so that the end product is not overproduced. When the end product is used by the cell, more is allowed to be produced
Parts of endomembrane system
Nucleus, ER, golgi, membrane
Myosin
protein activate in contraction of muscle tissue. They have alternating filaments with actin filaments. They contain myosin heads that move along actin filaments using ATP. The filaments are pulled over myosin heads causing contraction
Cristae
Part of inner membrane of mitochondria that fold to increase surface area
Nuclear lamina
gives support to nucleus, gives it spherical shape and strength, lies in the inside of the nuclear membrane to make it sturdy, like a cytoskeleton of the nucleus, fibers run in a matrix pattern to give it shape/support
