the cell Flashcards
what is the role of lysosomes?
they are sacs of digestive enzymes
- used for repair and removal of foreign matter
eg. white blood cells
what is the negative feedback loop and give an example?
is pregnancy or blood clots
in pregnancy oxytocin is released to the uterus causing more contraction
name 2 functions of the smooth endoplasmic reticulum ?
- calcium storage
eg. skeletal muscle - de-toxification
eg. liver - steroid production
eg. ovaries, testes
what do ribosomes and endoplasmic reticulum do?
ribosomes are responsible for making proteins. They read genetic instructions carried out from mRNA and assemble amino acids in the correct order to form a protein
there are two types of endoplasmic reticulum
-smooth and rough
smooth: involved lipid synthesis, detoxification, and calcium storage
rough: makes organelles, and transports proteins made by ribosomes, assists in folding
eg. insulin and digestive enzymes
what is the function of the peroxisomes?
its found in the liver
they are known as oxidative enzymes
- helps in metabolism like beta oxidation, lipid synthesis
- and detoxify various waste products
- breaks down toxic substances like hydrogen peroxide and convert it into water and oxygen using an enzyme called catalase
name three things that are controlled by homeostasis?
blood pH
blood volume
body temperature
blood pressure
water/electrolytes
o2/co2
nutrients and wastes
What cells are multi-nucleated and why? Which cells have no nucleus?
muscle cells or skeletal muscle cells are multinucleated : why because they result from the fusion of many precursor cells called myoblasts, and having multiple nuclei allows the large muscle fibers to efficiently manage the high demand for protein synthesis and cellular repair across their length
and red blood cells have no nucleus to allows more space for hemoglobin and the protein that carries oxygen
What cells will have many lysosomes?
white blood cells and liver cells
Give an example of where are microtubules used in cell function.
they are used to transport secretory vesicles
form mitotic spindle during cell division
What is the genetic theory of aging?
telomere shortening
- with each replication of DNA nucleotides are lost
as we age what gradually happens to our cells?
our cells gradually deteriorate
- lose function
-cant respond to stress
- #of body cells decrease
- lose integrity of the extracellular components
what are the structures making up the cell membrane?
- phospholipid bilayer (one end is hydrophilic and one end is hydrophobic) creates a semi-permeable membrane
- proteins:
integral proteins- these are proteins that span across the membrane and act as channels, carriers, or receptors facilitating transport and communication
peripheral proteins- outside surface of membrane, play role in signalling, structural support, and maintaining cells shape
cholesterol: are embedded within the phospholipid bilayer, they help stabilize the membranes fluidity making it less permeable to small water soluble molecules
carbohydrates: are often attached to proteins (glycoproteins) or lipids (glycolipids) on the extracellular surface of the membrane
- play a role in signaling, or cell recognition
glycoproteins: proteins that are attached to carbohydrate chains that are involved in cell recognition and immune response.
Glycolipids: lipids with attached carbohydrate chains that contribute to membrane stability and cell interactions
what is the role of enzymes?
enzymes are typically proteins that act as a catalyst they speed up chemical reactions within the cell
- lower activation energy, reduce the activation energy for the reaction to occur which speeds up the reaction
- catalyses metabolism
How do glucose molecules move across the membrane?
facilitated transport/ facilitated diffusion which is the process in which a carrier protein moves glucose from high concentration to low.
- this process does not require ATP
How do Na+ molecules move across the membrane?
- this uses active transport either secondary or primary
primary uses:
-which uses atp cus you are going against the concentration gradient
low to high
what is secondary active transport
- does not directly use atp but instead is powered by the [ ] gradient of one solute
- moved solute against their concentration gradient
symport: move in the same direction across the membrane
antiport: move in opposite directions across the membrane
what are three functions of a protein?
proteins can act as enzymes which speed up chemical reactions like digestion or metabolism
structural support
transport and storage
What is osmosis and diffusion?
diffusion: movement of molecules from an area of higher concentration to an area of lower concentration
- no ATP required
osmosis: Specific type of diffusion that involves the movement of water molecules across a semi-permeable membrane
water moves from an area of lower solute and high water concentration to an area of high solute concentration and low water concentration.
What is exocytosis?
this is a process of active transport known as vesicular transport
- exocytosis is a process by which cells transport materials out of the cell. it involves the fusion of a vesicle (a small membrane-bound sac) with the cell membrane to release contents into the extracellular space
what is endocytosis?
process in which cells take in materials from the outside environment by engulfing with their cell membrane, forming a vesicle that brings the substance into the cell.
ligand-mediated endocytosis
also known as a receptor-mediated endocytosis is a specific process where a cell absorbs substances from outside by binding them to a specific receptor on its surface. Once the ligand or the susbstance binds to the receptor, the cell membrane folds inward, forming a vesicle that brings the ligand receptor complex into the cell
eg. moves iron and antibodies
what is phagocytosis?
type of endocytosis where a cell engulfs large particles, such as debris bacteria and such then comes into the membrane to form a vesicle called a phagosome.
- the phagosome then fuses with a lysosome, where enzymes break down and digest the engulfed material.
- this is essential for immune response in white blood cells then they remove pathogens and cellular debris.
what is pinocytosis?
cell absorbs water molecules that are present in the extracellular fluid, it helps the cell take in nutrients, ions, and other molecules from its environment
What factors determine the rate of diffusion?
- concentration gradient - the greater the difference in concentration between two areas, the faster the rate of diffusion
- molecules move more quickly from high to low concentration when the gradient is steep - temperature- higher temp the more kinetic energy of molecules
- diffusion distance - the shorter the distance over which diffusion occurs, the faster the rate
