Cell physiology Flashcards
1
Q
What is intracellular fluid?
A
water in the animal that is found inside the cell
2
Q
What is extracellular fluid?
A
fluid outside the cell
3
Q
What is interstitial fluid?
A
extracellular fluid specifically found in tissues
4
Q
What are positively charged ions called?
A
cations
5
Q
What are negatively charged ions called?
A
anions
6
Q
Anions and cations are capable of conducting electrical current in solution so they are called…?
A
electrolytes All ions are called electrolytes
Acid and bases are also electrolytes because they can dissociate in water and can conduct an electrical pulse.
7
Q
Acids are molecules that release protons and are called…
A
proton donors
8
Q
Bases release hydroxyl ions, which readily bind to free hydrogen ions (protons) so they are called…
A
proton receivers
9
Q
What two things happen when hydroxyl anion and a hydrogen cation unite?
A
water is formed and the acidity of the solution is reduced.
10
Q
The more free protons or hydrogen ions (H+) in a solution, the greater is its __________?
A
Acidity
11
Q
The greater the concentration of hydroxyl ions, the more ______ or _____ the solution becomes.
A
basic or alkaline
12
Q
Tissue fluids are loaded with…?
A
electrolytes, fatty acids, vitamins, amino acids, regulatory hormones, and dissolved gasses
13
Q
The cell membrane is generally considered to be ________ because it allows some molecules to pass through, but not others.
A
selectively permeable
In addition, the cell membrane may be impermeable to some substances and freely permeable to others
14
Q
What is the concentration gradient?
A
the spectrum between the most concentrated region and the area that is least filled with molecules
15
Q
Diffusion can be defined as …?
A
the process of moving down the concentration gradient (as molecules move from an area of high concentration to a region of low concentration they are said to be moving down the concentration gradient) Example: placing a drop of lemon in your tea - the drop spreads out until evenly distributed
16
Q
What does the rate of diffusion depend on?
A
the temperture - diffusion occurs faster in a hot liquid than in a cold liquid
17
Q
What determines whether or not a molecule may pass through the cell membrane by passive diffusion?
A
- Molecular size (water passes but glucose cannot)
- Lipid solubility (alcohol, steroids, and gases)
- molecular charge (channels selectively allow certain ions to pass - ex: chloride channels only permit chloride ions to pass)
18
Q
What is facilitated diffusion?
A
the diffusion of some large molecules and non-lipid soluble molecules across the cell membrane with the assistance of an integral protein or carrier protein that is located in the bilayer. Requires no energy or ATP Example: movement of glucose into the cell
19
Q
Facilitated diffusion can limited… how?
A
by the number of carrier proteins that are available
Hormones such as insulin, plays an important role in controlling the activity of the glucose-specific carrier proteins and can act on them to speed up their rate of transport.
20
Q
What is Osmosis?
A
the passive movement of water through a semipermeable membrane into a solution in which the water concentration is lower (water seeks to dilute; it will go to the concentrated area to dilute it - higher concentration in the blood, water will leave to go to the blood
21
Q
What is a concentration balance or equilibrium?
A
when the movement of water occurs to achieve the same concentration of solution on both sides of a semipermeable membrane
22
Q
What is osmotic pressure?
A
the force of water moving from one side to the other
23
Q
True or False Osmosis occurs in the opposite direction of diffusion and in osmosis the water, not the solute is moving.
A
True
24
Q
True or False Osmosis requires a selective membrane, whereas diffusion does not.
A
True
25
When the extracellular fluid has the same concentration as the intracellular fluid it is called?
isotonic
26
If the extracellular fluid is _________, however, the inside of the cell is more concentrated than the outside (water flows into the cell and causes it to swell and possibly burst?
hypotonic
27
If the extracellular fluid is ____________ and more concentrated than the cytoplasm, water is excreted into the extracellular space, causing the cell to shrink and become shriveled.
hypertonic
28
The difference between the osmotic pressure of blood and the osmotic pressure of interstitial fluid or lymph is called the _______________.
oncotic pressure
29
What is subcutaneous edema?
when fluid leaks into the tissue under the skin
30
What is it called when fluid leaks into the abdomen?
ascites
31
Filtration is based on a ____________ gradient.
pressure
32
In filtration, what is the force that pushes a liquid?
hydrostatic pressure
EX: blood pressure - pressure generated by pumping heart
One of the best examples of filtration in animals is evident in the kidney - pushing fluid through, filtering it in the kidneys (water will go through)
33
Where is most of the water in animals found?
Most of the water in animals is found inside the cell and is called intracellular fluid.
34
What is diffusion? Is it an active or a passive membrane process?
Diffusion can be defined as the process of moving down the concentration gradient from an area of high concentration to a region of low concentration. Diffusion is a passive membrane process.
35
What molecules are more likely to diffuse into a cell? What three principles are involved?
Water, oxygen, and carbon dioxide are more likely to diffuse into a cell. The three principles involved are:
1. Molecular size: Very small molecules like water (H2O) may pass through cellular membrane pores (approximately 0.8 nm in diameter), but larger molecules like glucose cannot.
2. Lipid solubility: Lipid-soluble molecules (e.g., alcohol and steroids) and dissolved gases (e.g., oxygen [O2] and carbon dioxide [CO2]) can pass through the lipid bilayer with ease, whereas other molecules may not.
3. Molecular charge: Ions are small in size, but their charge prevents easy passage through the membrane pores. Specialized pores called channels selectively allow certain ions to pass through but not others.
36
How is facilitated diffusion different from simple diffusion? What is the limiting factor in the rate of facilitated diffusion?
Facilitated diffusion requires the assistance of an integral protein or carrier protein located in the bilayer. Small, lipid-soluble molecules, can pass through the cell membrane via simple diffusion. The limiting factor in the rate of facilitated diffusion is the number of available carrier proteins.
37
What effect does a hypotonic solution have on a cell? What passive membrane process causes this effect?
If the extracellular fluid is hypotonic, the inside of the cell is more concentrated than the outside. In this scenario, water flows into the cell and causes it to swell and possibly burst. This effect is due to the process known as osmosis.
38
What is the relationship between hydrostatic pressure and filtration?
Filtration is based on a pressure gradient. Liquids may be pushed through a membrane if the pressure on one side of the membrane is greater than that on the other side. The force that pushes a liquid is called hydrostatic pressure.
39
What is another name for hydrostatic pressure in the body?
Blood pressure
40
The movement of molecules and substances across the cell membrane is considered ______ when the cell is required to use energy.
active
41
Some molecules are unable to enter the cell via the passive routes, because....?
1- they are not lipid soluble and therefore cannot penetrate the lipid bilayer
2- they are too large to pass through a membrane pore
3- they are on the wrong side of the concentration gradient
42
What are the two processes used to actively move substances into or out of the cell?
1 - active transport
| 2 - cytosis
43
What are some Similarities and differences between facilitated diffusion and active transport?
both rely on carrier proteins with a specific binding site but active transport does not require a concentration gradient.
44
What is kinetic energy?
Activity that Molecules do when they are constantly moving, gyrating (to move in a circle or spiral around a fixed point) and at times bouncing into one another. This movement can be increased in warmer temperatures and slowed in cooler ones.
45
What must some amino acids and ions rely on in order to enter and exit cells without the assistance of a concentration gradient?
they must rely on a form of energy called ATP, to assist in their transport across the cell membrane
46
Many active transport systems move more than one substance at a time (against the concentration gradient. If all of the substances are moved in the same direction it is called __________? If some substances are moved in one direction and others moved in the opposite direction, the system is called ________? What is an example of this system?
What does the active transport system's rate of transport depend on?
symport system
antiport system
The antiport Na (Sodium) and K (potassium) pump
- diffusion is ongoing, pumping Na in the cell, K out of the cell
the concentration of sodium ions in the cell
47
What does ATP stand for?
adenosine triphosphate
48
What are the most common cations (positively charged ions) in the cell?
Na and K
49
What is cytosis?
another mechanism for bringing nutrients into the cell and ejecting waste.
50
Is cytosis an active process?
yes, it requires ATP
51
What are the two types of cytosis?
endocytosis which means going into the cell and exocytosis which means going out of the cell
52
Endocytosis enables large particles, liquid substances, and even entire cells to be taken into a cell by ___________.
engulfing
53
1) If the cell engulfs solid material, the process is called?
2) The vessel formed from phagocytosis is called a? 3) If the cell engulfs liquid, the process is called?
4) What is receptor-mediated endocytosis?
5) What is exocytosis?
6) What is excretion?
7) What is secretion?
1) phagocytosis means cell eating
2) phagosome
3) pinocytosis means cell drinking
4) receptor-mediated endocytosis is very specific, occurring in cells that have specific proteins in their plasma membrane. These proteins act as specialized receptor sites for insulin or ligands (such as hormones, iron, and cholesterol) attaching to the cell to allow glucose to go in
5) substances that cells may export from the intracellular environment into extracelluar space Ex: what a gogli apparatus does
6) getting rid of waste products
7) endocytosis of manufactured molecules
54
What is voltage in relation to the cell?
a potential electrical energy created by the separation of opposite charges
55
When is a membrane process considered “active”?
The movement of molecules and substances across the cell membrane is considered active when the cell is required to use energy (ATP). They cannot move through the plasma membrane passively.
56
How do electrolytes enter the cell?
Electrolytes enter cells via active transport without the assistance of a concentration gradient.
57
What is the difference between a symport and an antiport system?
Many active transport systems move more than one substance at a time. If all the substances are moved in the same direction, the system is called a symport system. However, if some substances are moved in one direction and others moved in the opposite direction, the system is called an antiport system.
58
Describe how sodium and potassium enter and exit the cell.
Because of the concentration gradient of sodium (Na) and potassium (K), potassium tends to diffuse out of the cell and sodium diffuses in. To maintain appropriate levels of intracellular potassium and extracellular sodium, the cell must pump potassium into the cell and move out sodium. Because diffusion is ongoing, the active transport system must work continuously. The rate of transport depends on the concentration of sodium ions in the cell. ATP is provided by cellular respiration and, with the assistance of the enzyme ATPase, is broken down for use as energy on the inner surface of the cell membrane. The pump can cycle several times using just one molecule of ATP, so that for every molecule of ATP, two K ions are moved intracellularly and three Na ions are moved extracellularly.
59
Describe the three types of endocytosis.
The three types of endocytosis are phagocytosis, pinocytosis, and receptor-mediated endocytosis.
60
What is the difference between excretion and secretion? These are both examples of what?
Excretion is the movement of waste products from the intracellular to the extracellular environment, and secretion is the movement of manufactured molecules from the intracellular to the extracellular environment. Both are examples of exocytosis.
61
What are the principal ions involved in maintaining a cell’s resting membrane potential?
Sodium and potassium
62
Is there normally a higher concentration of sodium inside or outside of the cell? Where is there a higher concentration of potassium?
Sodium is 10 to 20 times higher outside the cell than it is inside. Potassium is 10 to 20 times higher inside the cell than outside.
63
In multicellular animals, cells are divided into what 2 broad categories based on the way they divide?
Reproductive cells which are found in ovaries and testicles and give rise to eggs and sperm - divide via a process - meiosis
Somatic cells - include all of the cells except the reproductive cells - divide via a process - mitosis
64
What is mitosis?
a cell divides by separating into two roughly equal parts
65
The life cycle has been divided into 2 major periods, what are they?
Interphase - when the cell is growing, maturing, and differentiating (period between cell divisions)
Mitotic phase - when the cell is actively dividing
66
What are the 3 subphases of interphase?
growth one, synthetic, and growth two - cell growth occurs throughout all of them
67
What is growth one (G1)?
the first part of interphase - can last for variable periods (min, weeks, years)
- can be defined by intensive metabolic activity and cellular growth, cell doubles in size and the number of organelles also doubles. In addition, centrioles begin to replicate in preparation for cell division
68
What is the synthetic phase?
is marked by DNA replication - new histones are formed and are assembled into chromatin, forming new identical replicas of the genetic material
69
What is growth two (G2)?
it is very brief and includes the sythesis of enzymes and proteins necessary for cell division and continued growth of the cell. The centrioles complete their replication by the end of this phase.
70
Is interphase a time when the cell is resting? Why or why not?
No, because it is carrying out metabolic activities during interphase. Before each cell can divide, a perfect copy of the DNA must be created to pass on to the daughter cells. This replication occurs during interphase.
71
What are the four stages of the mitotic phase?
Prophase, metaphase, anaphase, and telophase
72
What happens during the prophase stage?
1. Prophase: Chromatin coils and condenses to form barlike chromosomes that are visible with light microscopy. These chromosomes are composed of two identical chromatids linked together at a constriction in their middle known as the centromere or kinetochore. The cytoplasm becomes more viscous as microtubules from the cytoskeleton are disassembled and the cell becomes round. Two pairs of centrioles form anchors on which new microtubules are constructed, and as the microtubules lengthen, they push the centrioles farther and farther apart. In this way a mitotic spindle is formed that provides the structure and machinery necessary to separate the chromosomes. Because transcription and protein synthesis cannot occur while the DNA is tightly coiled, the appearance of chromosomes marks the cessation of normal synthetic processes. Prophase is thought to conclude with the disintegration of the nuclear envelope.
73
What happens in the Metaphase stage?
2. Metaphase: Chromosomes line up in the exact center of the spindle, known as the equator. The chromosomes are evenly spread apart and form what is called the metaphase plate midway between the poles of the cell. The centromere of each chromosome is attached to a single spindle fiber.
74
What happens in the Anaphase stage?
3. Anaphase: The centromeres of the chromosomes split apart and each chromatid becomes its own chromosome. The spindle fiber separates, each spindle segment shortens, and the twin chromosomes are pulled away from each another. The chromosomes take on a V shape as they are dragged at their midpoint toward the centrioles at opposite ends of the cell. The cell becomes elongated, and the cytoplasm begins to constrict along the plane of the metaphase plate. Although anaphase is the shortest phase of mitosis and usually lasts only a few minutes, its importance is clear in light of the devastating consequences if an error were to occur in chromosome separation. In anaphase the advantage of separating compact bodies of chromosomes, rather than long thin threads of chromatin, is particularly obvious.
75
What happens in the Telephase stage?
4. Telophase: Begins when chromosomal movement stops. The chromosomes, having reached the poles, begin to unravel, elongate, and return to a diffuse threadlike form (chromatin). A nuclear envelope appears around each new set of chromosomes, and nucleoli appear in each nucleus. The microtubules that made up the spindle in the earlier phases of mitosis disassemble, and a ring of peripheral microfilaments begins to squeeze the cell into two parts. Ultimately, the cell pinches itself in half, dividing the cytoplasm and forming two completely separate daughter cells. The process of cytoplasmic division is called cytokinesis and marks the end of telophase.
76
. Why is it important for chromatin to coil and form discrete chromosomes before cell division?
Transcription and protein synthesis cannot occur while the DNA is tightly coiled.
77
What three factors play a role in the control of cell division?
Normal cells stop dividing when they come into contact with surrounding cells. This phenomenon is called contact inhibition. 2. Growth-inhibiting substances may be released from cells when their numbers reach a certain point. 3. A number of checkpoints are reached during cell division when the cell reassesses the division process. These checkpoints occur during the G1 and G2 phases of interphase.
78
What is the genetic basis of cellular differentiation?
The position of genes in chromosomes determines the genetic basis of cellular differentiation. Some genes may be located on a region of the chromosome that is available for transcription, whereas other genes may be located inside the molecule and cannot be reached by transcription molecules. We say that one gene is “turned on” while the other gene is “turned off.” Genes can be turned off permanently or temporarily. Chromosomes are dynamic in their ability to twist, so that a gene that was once inaccessible on the inside can be moved to the outside of the molecule for use. Differentiation involves the temporary or permanent inhibition of genes that may be active in other cells.
79
What are the first 3 steps that allow the DNA to replicate in the interphase stage?
Step one: The chromatin uncoils from the super-helical and helical formations
Step two: The DNA unwraps and separates from histone proteins.
Step three: A special protein called a helicase enzyme indicates the untwisting of the DNA helix and separates portions of the DNA into.two nucleotide chains.
80
What is important in maintaining cellular homostasis?
amount of ions, the type of ions, and the distribution of ions
81
What is an ion?
charged particles
82
What type of particles (ions) exist within the intracellular and extracellular environments of all tissues?
charged particles (ions)
83
What is a neuron?
cells of the nerves that are structually composed of a cell body (perikaryon), dendrites, & an axion
84
What is the basis of our nerve system?
nerve or neuron
85
What does our tissues throughout our body try to do?
maintain homostasis (charges does this also)
86
What is membrane potential or voltage?
Voltage is potential electrical energy created by the separation of opposite charges ( the charge on one side to the other)
87
What charge does the outside of the cell have?
no charge (cytoplasm also has no charge)
88
How does the cell control the distribution and flow of ions that create the membrane potential?
by both active and passive membrane processes which places more positviely charged ions on the outside of the cell than on the inside. For every cycle of active transport, 3 sodium molecules exit the cell for every 2 potassium molecules that are retrieved.
89
What could alter resting membrane potentials?
environmental tonicity, osmotic pressures temperature, & contact with neighboring cells
90
What could alter the flow of metabolites & the behavior of some structural & enzymatic proteins?
altering the resting membrane potentials
91
What are the principle ions involved in maintaining membrane potential?
K - potassium and Sodium - Na
92
Are there more postassium ion in the inside of the cell or outside the cell?
inside the cell
93
How does potassium moe out of the cell?
diffusion
94
Is sodium more concentrated inside the cell outside the cell?
outside the cell
95
How does sodium enter the cell?
active transport
96
What does our tissues throughout our body try to do?
maintain homostasis (charges does this also)
97
What is membrane potential or voltage?
Voltage is potential electrical energy created by the separation of opposite charges ( the charge on one side to the other)
98
What charge does the outside of the cell have?
no charge (cytoplasm also has no charge)
99
How does the cell control the distribution and flow of ions that create the membrane potential?
by both active and passive membrane processes which places more positviely charged ions on the outside of the cell than on the inside. For every cycle of active transport, 3 sodium molecules exit the cell for every 2 potassium molecules that are retrieved.
100
What could alter resting membrane potentials?
environmental tonicity, osmotic pressures temperature, & contact with neighboring cells
101
What could alter the flow of metabolites & the behavior of some structural & enzymatic proteins?
altering the resting membrane potentials
102
What are the principle ions involved in maintaining membrane potential?
K - potassium and Sodium - Na
103
Are there more postassium ion in the inside of the cel or outside the cell?
inside the cell
104
How does potassium moe out of the cell?
diffusion
105
Is sodium more concentrated inside the cell outside the cell?
outside the cell
106
How does sodium enter the cell?
active transport
107
DNA replicates during interphase, list the steps of this process.
1. chromatin uncoils from the super-helical and helical formations
2. The DNA unwraps and separates from histone proteins (get protein out of the way)
3. A special protein called a helicase enzyme initiates the untwisting of the DNA helix - unzips the DNA
4. Any thing that unzips is going to be a complimentary pair (nucleotides - purines - adenine, and guanine - always bond to pyrimidines - thymine and cytosine)
5. Enzymes come in and start replicating (helps speed up reaction - primases)
6. How primases says start here by attaching 10 nucleotide (bases) - primer (RNA)
7. DNA - polymerase (many enzymes) - replicates the DNA chain on base pairs
8. Polymerase moves in one direction - takes over the leading strand
9. histones come back in - help it rewind after DNA has been replicated. lagging strands put on in fragments not made continously
10. Now have 2 strands of DNA - where do they meet at the centromere.
