Cellular and Membrane Flashcards
What does the term cell cycle refer to?
It refers to the events that somatic cells which include all of the cells in our bodies, except the reproductive cells go through from the moment they are formed until the moment they divide into two identical, daughter cells
How long does a cell cycle last?
It varies in length, depending on the type of cell for rapidly dividing cells like skin cells it takes less than a day or as for other cells like liver cells it can last year’s
What are the two phases of the cell cycle?
Interphase in mitosis
What happens during interphase in the cell cycle?
It is the longest part of the cell cycle, and it is a state of preparation during which the cell carries out its cell functions, grows and replicate its DNA to prepare for mitosis
What happens during mitosis in the cell cycle?
This is when the cell divides into two daughter cells, and separates the replicated DNA into two distinct nuclei, and the separation of the daughter cells into two distinct cells called cytokinesis
What are the four sub phases of mitosis?
Prophase, metaphase, anaphase and telophase, then immediately followed by cytokinesis
What does the G0 phase represent?
A phase outside the cell cycle, because while the cells are living, they are neither dividing nor preparing to divide
What is hyperplasia?
Refers to the process were cells in an organ or tissue increase in number
What is hypertrophy?
It is when these cells in an organ or tissue increase in size
What is an example of physiologic hypertrophy?
It is like lifting a 10 pound sack of potatoes, which puts a bigger functional demand on your skeletal muscles in response, the muscle cells produce more proteins or myofilaments and get larger in size, allowing the biceps as a whole to generate more force as a result, your muscle also becomes bigger and tougher
What is an example of pathologic hypertrophy?
It is when the heart undergoes hypertrophy to deal with high blood pressure or hypertension and hypertension. The heart has to pump blood against a higher resistance, and cardiac myocytes, once again, adapt by increasing the synthesis of myofilaments, causing individual cells to get bigger.
Does hyperplasia occur in relatively permanent cells like cardiac nerve and adult skeletal muscle tissue?
No hyperplasia doesn’t occur in relatively permanent tissues without stem cells like cardiac nerve and adult, skeletal muscle tissue
What are two types of hyperplasia and in what tissues or organs does each typically occur?
Compensatory, hyperplasia and hormonal hyperplasia.
Compensatory hyperplasia occurs in organs that regenerate like the skin lining of the intestines, the liver and bone marrow hormonal hyperplasia occurs in organs that are regulated by hormones like organs in the endocrine and reproductive system
What is an example of physiologic hyperplasia?
When an enlargement of the female breast during pregnancy
What is an example of pathologic hyperplasia?
Having excessive hormonal stimulation for example, if there is an overproduction of estrogen by an ovarian tumor, it can lead to excessive endometrial growth, also called endometrial hyperplasia
Is hyperplasia synonymous with cancer
No, but hyperplasia is sometimes associated with cancer. Normally hyperplasia is an adaptive response to stress, so it’s tightly regulated process meaning the tissues don’t grow out of control that’s different from cancer where there’s uncontrolled cell division however, as cells divide in hyperplasia some can mutate and that’s how hyperplasia can result in dysplasia, and eventually into cancerous malignancy
What is the definition of atrophy in the body?
Reduction in the size of a cell organ or tissue after it has attain normal, mature growth, or either a decrease in cell number or cell size
What is apoptosis?
Controlled type of cell death
Is muscle atrophy reversible?
Yes, except for very extreme situations
What is aplasia?
No development of a tissue or organ during embryogenesis
Defined the term hypoplasia
Under development or formation of a tissue or organ during embryogenesis
What is metaplasia?
When a mature, differentiated cell type is replaced by another mature, differentiated cell type often this happens because there’s an environmental stressor that the new cell type is better suited to handle
Is metaplasia reversible
Yes
What is dysplasia?
The tissue develops a large number of immature cells that have weird shapes typically due to chronic environmental stressors
Which type of cellular adaptation is most likely to develop into cancer
Dysplasia
What are stem cells?
Non-differentiated, non-specialized cells of the body found in blastocysts that can become any type of body cell
What are transcription factors?
They are typically proteins that determine which area of the DNA code will get transcribed into mRNA, which then can eventually be used to make specific proteins that can impact what the cell will look like and what a cell will do
What are somatic stem cells?
Non-embryonic stem cells that are found in cells in the body like muscle skin, liver and bone marrow
Which type of stem cell can differentiate into more cell types?
Embryonic stem cells
What is selective permeability of the cell membrane?
It helps regulate what comes in or out of the cell
What are the two types of transport across the cell membrane and how are they different?
Passive transport, which requires no energy and active transport, which requires energy in the form of adenosine triphosphate
What are the three types of passive transport?
Diffusion, facilitated, diffusion and osmosis
What is diffusion?
It helps small nonpolar molecules like oxygen and carbon dioxide move across the membrane from an area of high concentration to low concentration down the concentration gradient
When does diffusion stop?
When there are equal concentrations of the molecules on both sides of the cell membrane
What is meant by the term concentration gradient
The difference in concentration of a molecule between the intracellular fluid and extracellular fluid
What is facilitated diffusion?
It helps larger molecules and polar molecules move across the membrane, using transport proteins, like channels and carrier proteins
What is the difference between channels and carrier transport proteins?
Channels are not very specific and they can open or close to allow water and small polar molecules like ions that is dissolved in it to pass through carrier proteins are very specific. They have special binding sites that only allow certain molecules to bind to them, and they also have gates at both ends, which opens sequentially.
What is osmosis?
It describes the movement of water across the cell membrane. It’s a special case of facilitated diffusion, because water uses channels called aquaporins to move across the membrane.
What drives osmosis?
It is driven by osmotic pressure, which is a force, determined by the difference in solutes between the two sides, osmotic pressure, drives water from the hypotonic side, or the one with lower concentration of solutes to the hypertonic side, or the one with a higher concentration of solutes
How are molecules transport against a concentration gradient
Active transport across the cell membrane, which requires energy
What are the two kinds of active transport and how are they different?
Primary and secondary active transport, primary active transport directly uses ATP as fuel, and it’s done by enzymes, called ATPase. secondary active transport, does not directly require ATP, but uses an electrochemical gradient
How does the sodium potassium pump work?
For each ATP molecule, it pumps three ions of sodium out of the cell while at the same time pumping two ions of potassium into the cell. The resulting difference in concentrations of ions on either side of the membrane creates a concentration gradient, but since ions also carry electrical charges it’s considered an electrochemical gradient, and the cell can use this in secondary active transport.
What is endocytosis?
A form of boat transport, where the cell membrane invaginate and pulls in something from the outside
What is exocytosis?
A form of bulk transport were a vesicle from within the cell pushes something out of the cell
When is equilibrium reach during the process of osmosis
When the net movement of water across the membrane is zero
If the concentration of solute in solutions, a and B, on either side of the membrane is the same what is the tonicity of these solutions to one another?
A and B are isotonic to each other
If the concentration of solute in solution a is higher than the solution b, what is the tonicity of these solutions to one another
Solution a is hypertonic to solution b and solution b is hypotonic solution a
If the concentration of solute in solution a is higher than the solution b, what is the expected direction of water molecule movement
Since solution a is hypertonic to solution b its osmotic pressure increases, and we expect to see a bigger net migration of water molecules to solution a until the concentration of the solutes is equal on both sides
What is endocytosis?
A form of boat transport that cells used to engulf extracellular material that uses energy from adenosine triphosphate
What is exocytosis?
A form of bulk transport that cells used to expel material into the extracellular space that uses energy from adenosine triphosphate
What are the three types of endocytosis?
Phagocytosis pinocytosis and receptor mediated endocytosis
What is phagocytosis?
A type of endocytosis, where cells eat, debris, bacteria, and dead cells to bring them into the cell, forming a phagosome
What is pinocytosis?
A type of endocytosis, where cells drink the cell membrane invaginate’s to form a small cup around the portions of extracellular, fluid and solutes that are dissolved in it then the edges of the cup come together, forming a vesicle
Where in the cell does exocytosis begin?
In an organelle called the Golgi apparatus
What is the process of exocytosis?
In the Golgi apparatus, the proteins, lipids, and hormones that are generated in the rough Endo plasmic, reticulum and smooth Endo plasmic reticulum are packaged into a vesicle that can be moved around the cell using the cytoskeleton. The vesicle moves towards the cell surface, fuses with the cell membrane and ruptures on its external side, spilling its contents into the extracellular space
What are the two major fluid compartments in the body?
Intracellular fluid and extracellular fluid
How much is the average percent of total body water weight in humans?
60% of body weight on average
What is the breakdown of total body water in intracellular and extracellular fluid?
2/3 or 40% of body weight is intracellular fluid the other 1/3 or 20% of body weight is extracellular fluid. This is also known as the 60 40 20 rule.
What are the two subdivisions of extracellular fluid?
Interstitial, fluid and plasma
What is interstitial fluid?
Fluid surrounding the cell
What is plasma?
Fluid that circulates within blood vessels
What is osmolarity and how is it measured?
The concentration of a solution it is measured as the number of particles of solute per liter of solution
If the osmolarity of a specific solute in the ECF is higher than the ICF what is likely to happen
Water will flow in the direction of more solutes to lower the concentration and maintain the balance through osmosis
Regarding ECF concentration, what does the term iso osmotic disturbance mean?
There is no change in ECF osmolarity
Regarding ECF concentration, what does the term hyperosmotic disturbance mean?
There is an increase in ECF osmolarity
Regarding ECF concentration, what does the term hypoosmotic disturbance mean?
There is a decrease in ECF osmolarity
What establishes a cells resting membrane potential
Differences in ion concentration, and charge on each side of the cell membrane and permeability across the membrane
In general, what ions do we expect to see a higher concentration of outside the cell in the ECF
Sodium chloride and calcium
In general, what ions do we expect to see a higher concentration of inside the cell in the ICF
Potassium and a variety of negatively charged anions
Which ion can get across the cell membrane through leak channels?
Potassium
What is the electrostatic gradient in the cell membrane?
The difference in charge across the cell membrane that acts as a driving force to cause a molecule to move across the membrane
What does the equilibrium potential for an ion represent?
The point when an ion moving across the membrane due to the concentration gradient equals the ion, moving the other way into the cell due to the electrostatic gradient. This is also called the Nernst potential.
What is the equilibrium potential of an ion dependent on?
The equilibrium potential of an ion is dependent on two things, the concentration gradient for the ion and the cell being permeable to that ion
What does the Nernst equation tell us?
It tells us the equilibrium potential for each ion
Based on the difference in membrane permeability to different ions, the cells membrane resting potential is generally closest to which ions equilibrium potential
Potassium the membrane is much more permeable to potassium, so the resting membrane potential is generally closest to the equilibrium potential of potassium
What is homeostasis?
The processes working to maintain the body’s internal stability within normal limits even with changes to the external environment
What is the primary mechanism to maintain homeostasis?
Negative feedback, the body senses, change, and activates mechanisms that negate or reverse it
What is an example of negative feedback system to maintain homeostasis
Control of body temperature with an increase in body, temperature due to exercise or outside heat the brain acts as a control center and senses. The body temperature is above a setpoint and activates effectors to decrease the body temperature via vasodilation and or sweating when body temperature is returned to normal. The brain receives a negative feedback signal to stop decreasing body temperature.
How does a positive feedback system work to maintain homeostasis?
Positive feedback is a self amplifying cycle, in which a physiological change leads to an even greater change in the same direction
What is an example of a positive feedback system to maintain homeostasis?
Breast feeding a baby suckling on the mothers nipple activates McCanna receptors in the nipple which sends signals to the brain to release hormones to stimulate muscle contraction in milk ejection. There is no mechanism for suppression of the response. It just continues to build until the suckling stops.
What is the cell membrane made from?
A double layer of phospholipid molecules
Which part of the phospholipid membrane is hydrophilic? What is it made from and which way is it oriented?
The head negatively charged phosphate, oriented outwards
Which part of the phospholipid membrane is hydrophobic? What is it made from and which way is it oriented?
The tail, 2 fatty acids, and oriented in words
Can oxygen easily pass through the semi permeable phospholipid cell membrane
Yes
Can carbon dioxide easily pass through the semi permeable phospholipid membrane
Yes
Can glucose easily pass through the semi permeable Phospho, lipid membrane
No
What is the function of protein channels in the phospholipid bilayer?
To allow water and specific ions, like sodium and potassium to come in and out of the cell
What is the cytoskeleton made from?
Proteins like microfilaments, microtubules and intermediate filaments
What are the functions of the cytoskeleton?
To provide structural stability and allow the cell to change shape. This is helpful for muscle contraction, cell division, and cell movement.
What makes up the cytoplasm?
The cytosol and cell organelles
What is intracellular fluid called?
Cytosol
Which organelle is highly specialized in houses genetic material
The nucleus
What is a gene?
It contains DNA that determines the characteristics of the cells, proteins and intracellular enzymes that control cytoplasmic and nuclear activities and also controls and promotes cell reproduction
What is DNA?
A long tightly coiled molecule with some parts that code for genes connected by other parts that don’t code for genes
What is a chromosome?
A folded and tightly packed form of DNA made of chromatin
What is the name of the process that turns DNA into RNA?
Transcription
What are ribosomes made of and what is their function?
They are formed by the nucleolus in the nucleus they convert mRNA into a string of amino acids, which form proteins
What is the process where are ribosomes convert mRNA into amino acids and then into proteins
Translation
What does a stop codon do?
It is located on the mRNA strand, and tells the ribosome to stop building the protein during translation
What organelle does the ribosome attach to during protein synthesis?
The rough endoplasmic reticulum
What is the function of the smooth endoplasmic reticulum?
It is responsible for lipid synthesis, detoxification in liver cells, steroid hormone synthesis in glandular tissues
What is the function of the Golgi apparatus?
It takes the proteins, lipids and hormones generated in the rough ER and smooth ER and packages them into vesicles that are distributed around the cell
Which type of vesicles are packaged in the Golgi apparatus
Transport vesicles that move within the cell and secretory vesicles that move molecules out of the cell through exocytosis
What is the function of a lysosome?
It is a membrane bound organelle filled with enzymes that help breakdown other molecules or organelles within the cell
What is the function of the mitochondria in a cell?
It is the powerhouse of the cell. These membrane bound. Organelles are involved with generating energy in the form of ATP to fuel cellular functions.
What is glycolysis?
A metabolic pathway that Cleaves, the six carbon glucose into 2 halves which are three carbon molecules called pyruvate
What is aerobic respiration?
A metabolic process that occurs when pyruvate created from glucose through glycolysis enters the mitochondria and goes through the citric acid or Krebs cycle and the electron transport chain to produce ATP this process produces about 32 molecules of ATP for every single glucose molecule
What is beta oxidation?
When the mitochondria uses fatty acids rather than glucose as a source of energy
What are the main roles of the cell membrane?
To define what’s inside the intracellular space, and what’s outside the extra cellular space, and to regulate what comes in or out of the cell
What is another name for the cell membrane?
Plasma membrane
What is the cell membrane made of?
A bilayer of phospholipid molecules with a negatively charged phosphate head a tail made of two fatty acids, and a skeleton made of glycerol
Is the head of the phospholipid molecule that makes up the phospholipid bi layer hydrophobic or hydrophilic?
Hydrophilic it likes water
Is the tale of the phospholipid molecule that makes up the phospholipid bi layer, hydrophobic or hydrophilic
Hydrophobic it does not like water
Is the tale of the phospholipid molecule that makes up the phospholipid bilayer Lipo phobic or lipophilic
Lipophilic it loves fats
In the phospholipid by layer, where are the head and tails oriented?
The hydrophobic tails are oriented in words where there are no water molecules, and the hydrophilic heads are oriented outwards in contact with water molecules
What does the term semi permeable in reference to the cell membrane mean?
The membrane allows some molecules to pass through but not others. This is mostly based on the molecule size polarity and charge.
Are small and nonpolar molecules like oxygen or carbon dioxide, able to pass through the cell membrane if so, do they pass through quickly or slowly?
Yes, they can diffuse through the membrane quickly
Are small and polar molecules like water able to pass through the cell membrane? If so, did they pass through quickly or slowly?
Yes, they can diffuse through the membrane, but it happens relatively slowly
Our large and nonpolar molecules such as retinol able to pass through the cell membrane if so, did they pass through quickly or slowly?
Yes, they can cross the cell membrane since they are nonpolar, but slowly because the molecule is so large
Are large in polar molecules, such as glucose able to pass through the cell membrane if so, did they pass through quickly or slowly?
They are unlikely to pass the cell membrane on their own
Are highly polar ions like sodium potassium, and chloride or molecules that possess a charge like amino acids able to pass through the cell membrane if so, do they pass through quickly or slowly
They cannot pass through the cell membrane on their own
What is the function of cholesterol in the cell membrane?
It makes the cell membrane fluid and durable at different temperatures
What is the function of transport proteins in the cell membrane?
They help move molecules that can’t freely diffuse across the membrane to get in and out of the cell
What are the two types of transport proteins?
Channels and carriers
What is the function of channel proteins?
They are transport proteins that open to form sort of a tunnel through the membrane through which water and ions can flow right through
What is a channel protein that allows water to flow into and out of the cell membrane?
An aquaporin channel proteins
What is the function of carrier transport proteins?
They are very specific they have special binding sites that only allow certain molecules to bind to them, and they have gates at both ends, which open sequentially
As an example of a carrier protein, how does the glucose transporter called GLUT4 work to get glucose into the cell
The GLUT4 transporter is open to the outside and waits for a glucose molecule when a glucose molecule binds to a site within the transporter the outer gate closes, and the inner gate opens the glucose than unbind’s and enters the cell. Then the transporter resets and waits for the next glucose molecule.
How do ATPases function as transport proteins?
These transport proteins, essentially enzymes, use the energy from ATP to actively pump various ions in or out of the cell against their concentration gradient that gives them their name these ATPases push ions from the side, with a low concentration over to the side with a high concentration
What is the function of cell adhesion molecules in the cell membrane?
They are integral transmembrane proteins, that anchor the cell in place by attaching it to other cells
What is the function of cell surface receptors?
They receive input from the outside and transmit it to the inside of the cell. The input is usually some thing that other cells produce like hormones, cytokines, or growth factors.
What type of carbohydrates can be bound to proteins or lipids in the cell membranes? What are their functions?
Caleco proteins are carbohydrates bound to proteins in the cell membrane and glycolipids are bound to lipids in the cell membrane. These glycoproteins and glycolipids are unique to each cell and helps cells recognize one another.
What is an example of glycoproteins and glycolipids in the cell membrane functioning for cell recognition?
An example is with immune cells, distinguishing normal cells from invading pathogens based on the glycoproteins and glycolipids on the cell surface
What is the function of the extra cellular matrix?
It forms the environment surrounding the cells and help provide structure and function to the tissues that are made from lots of cells together
What are the different tissue types?
Epithelial, connective, muscular and nervous
What are the three major molecules that make up the extracellular matrix?
Adhesive proteins, structural proteins, and proteoglycans
What is the function of adhesive proteins in the extracellular matrix?
They helped us stick the individual cells together and organize the tissue into any structure cells. Use adhesive proteins to anchor themselves to other cells and two molecules in the ECM adhesive proteins. Also help communicate messages from the ECM to the cell.
What is the function of structural proteins in the ECM?
Structural, proteins gift, tissues, their tensile and compressive strength. Examples are collagen’s elastin’s and keratin’s.
What is the most common type of structural proteins in the human body?
Collagen
What are important characteristics of collagen?
It is the most common type of structural protein in the body it resists tension, and it can also stretch
What are the four most common types of collagen?
Types I, II, III, and IV
Where is type one collagen found in the body
It is found in the bones, skin and tendons
Where is type to college in found in the body
It is found in cartilage
Where is type three collagen found in the body
In reticulin, a type of fiber found in the liver and the lymphatic system and blood vessels
Where is type four collagen found in the body
It is found in the basement membrane, Essentia protein that separates different types of cells like nerve cells from muscle cells
Which type of structural protein allows connective tissues, to regain their original shape after stretching
Alaston
Where is elastin found in the body
In ligaments blood vessels, skin, and lungs
Which type of structural proteins, tough, and found in hair and nails in the body
Keratin
What is the function of proteoglycans in the ECM?
Proteoglycans and water together form a gel like substance that hydrates and cushions the cells and it’s the main reason that it’s so abundant in cartilage
What is the cytoskeleton?
A network of proteins within the cell
What is the function of the cytoskeleton?
It gives each cell its shape, an anchor cell organelles in place. It also can change shape to allow the cell to move. Contract divide or pull in or push out molecules.
What three protein filaments make up the cytoskeleton
Actin filaments (microfilaments), intermediate filaments, and microtubules
What is the function of actin filaments?
To connect to one another to form a network located just below the cell membrane actin filaments slide closer together and further apart, allowing the cell to change shape during muscle contraction
What is another name for Actin?
Microfilaments
Which types of cells have lots of actin in myosin
Muscle cells
How do actin and myosin work together to cause muscle contractions?
Myosin filaments bind to actin filaments, and that’s what allows the actin to slide closer together and farther apart, which makes the muscle cells shrink and stretch during muscle contraction and relaxation
What is the role of actin filaments in mitosis?
At the end of mitosis, the cell has two sets of chromosomes that each sit in their own nucleus, a ring of actin filaments then forms around the center of the cell between the two nuclei this ring uses the sliding movement of Actin and myosin to help constrict, or squeeze the cell so that it pinches off into two new cells
What is the function of microtubules?
Microtubules help with intracellular transport, taking vesicles to and from the cell membrane and cellular organelles microtubules also play a role in cell division and help with cell movement
Place the cytoskeleton proteins in order from smallest to largest
Actin
Intermediate filaments
Microtubules
What is the function of intermediate filaments?
They fasten various organelles like the nucleus in place within the cell intermediate filaments also help anchor cells to neighboring cells through cell to cell junctions and help anchor the cells to their surrounding environment in the ECM
