Exam 2 Flashcards
(184 cards)
0
Q
This section of the nucleus is the location of ribosomal RNA synthesis.
A
Nucleolus
1
Q
This organelle consists of many flattened membrane stacks.
A
Golgi apparatus
2
Q
This organelle is an extensive network of membrane and can account for over have of the membranes in a cell
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Endoplasmic reticulum (ER)
3
Q
Photosynthesis occurs inside of this organelle.
A
Chloroplast
4
Q
The location of the majority of the DNA in a the cell.
A
Nucleus
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Q
This organelle is filled with digestive enzymes.
A
Lysosome
6
Q
This organelle acts as the “shipping and receiving center” of the cell.
A
Golgi apparatus
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Q
This the majority of ATP production in the cell occurs within this organelle.
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Mitochondria
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Q
The rough regions of this organelle have bound ribosome.
A
Endoplasmic reticulum (ER)
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Q
This organelle is surrounded by double membrane that is continuous with the endoplasmic reticulum.
A
Nucleus
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Q
This organelle is found in plant cells but not in animal cells.
A
Chloroplast
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Q
This organelle receives proteins from the ER, sorts them into different compartments, and the sends them to various destinations within the cell
A
Golgi apparatus
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Q
This structure, which allows cells to move, contains microtubules.
A
Flagella
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Q
During this phase, all of the kinetic bores of the sister chromatids are bound to microtubule and the chromosome line up in an imaginary plane between. The two spindle poles
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Metaphase
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Q
The nuclear envelope reforms during this phase
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Telophase
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Q
During this phase, the nuclear envelope fragments and microtubules start to invade the space that the nucleus once occupied.
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Prometaphase
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Q
During this phase,nth cohesion proteins that are holding the sister chromatids breaks, and the resulting daughter chromosomes began moving to their respective spindle poles.
A
Anaphase
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Q
During this phase,nth sister chromatids start to condense into tight structures.
A
Prophase
18
Q
Describe what occurs during the metaphase
A
- the centrosomes are now fully at the opposite poles of the cell
- the chromosomes convene on the metaphase plate
- for each chromosome, the kinetochores of each sister chromatids are attached to kinetochore microtubules coming from opposite poles
19
Q
The centrosomes are now fully at the opposite poles of the cell
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Metaphase
20
Q
The chromosomes convene on the metaphase plate
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Metaphase
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Q
For each chromosome, the kinetochores of each sister chromatid are attached to kinetochore microtubules coming from opposite poles
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Metaphase
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Q
Each duplicates chromosomes appears as two identical sister chromatids joined together at their centromeres and all along their arms
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Prophase
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Q
The chromosome condense, becoming more tightly coiled
—-Discrete chromosome are observable with a light microscope
chromosome condense and become visible
A
Prophase
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The motic spindle begins to form
Prophase
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The centrosomes start to migrate to opposite poles of the cell. (They pushed there by lengthening microtubules form the aster.)
Prophase (what happens when the mitotic spindle begins to form)
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Describe what happens in the stage of prophase
- The chromosomes condense, becoming more tightly coiled OR chromosome becomes condense and visible
- Each duplicated chromosome appears as two dental sister chromatids joined together at their centromeres and all along their arms
- The mitotic spindle begins to form
- The centrosomes start to migrate to oposites poles of the cell. (They are pushed there by lengthening microtubules form the aster)
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Describe what happens in the stage of prometaphase
- The nuclear envelope fragments
- Microtubules from the asters start to invade the area that was formerly occupied by the nucleus
- The chromosomes are fully condensed
- Kinetochores form at the centromere of each chromosome.
- Some of the microtubules attach to the kinetochores
- Microtubules that don't interact with kinetochore )non-kinetochore microtubules) interact with microtubules form the opposite pole of the spindle
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The nuclear envelope fragments
prometaphase
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Microtubules from the asters start to invade the area that was formerly occupied by the nucleus
prometaphase
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The chromosomes are fully condensed
prometaphase
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Kinetochores form at the centromere of each chromosome
prometaphase
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Some of the microtubules attach to the kinetochores
prometaphase
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Microtubules that don't interact with kinetochores (non-kinetochores microtubules) interact with microtubules coming from the opposite poles of the spindle
prometaphase
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starts with the cleavage of the cohesion proteins that are holding the two sister chromatids together
anaphase
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the two sister chromatids part and are not know as daughter chromosomes
anaphase
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the daughter chromosomes start moving toward opposite ends of the cells
anaphase
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Non-kinetochore microtubules from different poles overlap and motor proteins that connect the microtubules start walking them away from one another (using energy form ATP)
anaphase
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At the end of this phase there should be a complete set of chromosomes at each pole of the cell
anaphase
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Describe what happens during anaphase
- Anaphase starts with the cleavage of cohesion proteins that are holding the sister chromatids together
- --The two sister chromatids part and are now know s daughter chromosomes
- The daughter chromosomes start moving toward opposite ends of the cell
- -Non-kinetochore microtubules from different poles overlap and motor proteins that connect microtubules start walking them away from one another using energy from ATP
- --The elongates the cell an moves the poles away from each other
- At the end of anaphase, there should be a complete set of chromosomes at each pole of the cell
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Two daughter nuclei start to form in the new cells
telophase
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Nuclear envelop from the parent cell's nuclear enveolpw and other portions of the endomembrane system
telophase
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Nucleoli reappears
telophase
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Describe what happens in telophase
- Two daughter nuclei start to form in the new cells
- Nuclear envelope from the parent cell's nuclear envelope and other portions of the endomembrane
- Nucleoli reappear
- The chromosomes become less condensed
- Mitosis is now complete
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the chromosomes become less condensed
telophase
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mitosis is now complete
telophase
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the first Gap phase
G1
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The cell grows by producing proteins and cytoplasm
G1
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In a typical human cell, this could take 5-6 hours
G1
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Synthesis phase
S phase
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The cell grows by producing proteins and cytoplasm
S phase and G2 phase
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The chromosomes are duplicated in this phase
S phase
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Each set of duplicate chromosomes are called sister chromatids
S phase
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In a typical human cell, this could take 10-12 hours
S phase
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Second Gap phase
G2 phase
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The cell grows by producing proteins and cytoplasm
S phase and G2 Phase
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In a typical human cell, this could take 4-6 hours
G2 phase
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Describe the G1 phase
it is the first gap phase, the cells grow by producing proteins and cytoplasm (happens in every phase), and in a typical human cell it could take up to 5-6 hours
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Describe the S phase
it is the synthesis phase, the cells grow by producing proteins and cytoplasm ( like G1phase) the chromosomes are duplicated and each set of duplicate chromosomes are called sister chromatids, in a typical human cell this could tie 10-12 hours
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Describe G2 phase
is the second Gap phase. the cell grows by producing proteins and cytoplasm as in all the phase in the gap, in a typical human cell this could take 4-6 hours
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this describes the property of molecules, such as phospholipids, that have one hydrophilic end and one hydrophobic end
amphipathic
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describe amphipathic
this describes the property of molecules, such as phospholipids,that have one hydrophilic end and one hydrophobic end
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The breakage of a cell caused by being immersed in a hypotonic solution
plasmolysis
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describe plasmolysis
the breakage of a cell caused by being immersed in a hypotonic
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"Cell eating", the take-up of a large object by a cell The large object is taken into the cell inside of vesicle
phagocytosis
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describe phagocytosis
"Cell eating, the take-up of a large object by a cell. The large object is taken into the cell inside of a vesicle
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"Cell drinking", The take-up of solute (dissolved molecules) by a cell. The dissolved molecules
pinocytosis
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describe pinocytosis
"cell drinking" The take-up of solute, the dissolved molecules
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the contraction of a cell caused by being immersed in a hypertonic solution
crenation
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describe crenation
the contraction of a cell caused by being immersed in a hypertonic solution
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what is mitosis
mitosis is the process that ensures the equal division of chromosomes when one parent cell divides into two daughter cells. it ensures that each daughter cell receives on complete copy of the parental cell's DNA
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mitosis is the process that ensures the equal division of chromosomes when one parent cell divides into two daughter cells. It ensures that each daughter cell receives on complete copy of the parental cell's DNA
mitosis
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bulk transport, the transport of a large amount of solute or a very large particle across the membrane, occurs through
endocytosis and exocytosis ( the beginning processes and purpose of endocytosis and exocytosis)
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a vacuole is generated in the cell that contains the solute to be released
exocytosis
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this vacuole fuses with the plasm membrane
exocytosis
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this causes the solute to be released to the outside of the cell
exocytosis
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describe the process and purpose of exocytosis
- a vacuole is generated in the cell that contains the solute to be released
- this vacuole fuses with the plasma membrane
- this causes the solute to be released to the outside of the cell
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describe the process and purpose of endocytosis
- the cell takes in biological molecules and particulate mater by forming a new vesicle
- the three main types of endocytosis
1. phagocytosis
2. pinocytosis
3. receptor-mediated endocytosis
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cell eating
phagocytosis
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the cell engulf a particle by wrapping pseudopodia around it
phagocytosis
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the particle is packaged in a vesicle
phagocytosis
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the cell engulfs droplets of extracellular fluid into tiny vesicles
pinocytosis
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this creates vesicle filled with a solution the solutes that are outside the cell
pinocytosis
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allows cells to acquire bulk quantities of specific substances that may be quite dilute in the surrounding solution
receptor-mediated endocytosis
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receptor proteins, which bind to specific molecules (called a ligand) are embedded in the membrane
receptor-mediated endocytosis
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these receptors are located in specific sections of the membrane called coated pits
receptor-mediated endocytosis
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when the receptor binds to the ligand, it is taken into the cell in a vesicle
receptor-mediated endocytosis
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there is a lower concentration of penetrating solute outside the cell than inside the cell
hypotonic solution
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water flow into the cell
hypotonic solution
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causes animal cells to swell and possibly burst
hypotonic solution
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cause plant cells to swell, but the cell wall prevents them from bursting
hypotonic solution
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plant cells in this state are call turgid
hypotonic solution
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plant cells are generally healthiest in
hypotonic solution
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the concentration of non penetrating solute that is the same outside and inside of the cell
isotonic solution
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the rate of water leaving the cell is the same rate of water entering the cell
isotonic solution
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there is no change in the shape of animal or plant cells
isotonic solution
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animal cells are generally healthier in
isotonic solution
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the higher the concentration of non penetrating solute outside the cell than inside the cell
hypertonic solution
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water will flow out the cell
hypertonic solution
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animal cells will lose water, shrivel, and possibly die
hypertonic solution
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plant cell will pull away from the cell wall and possibly burst through plasmolysis
hypertonic solution
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The movement of solute that is unevenly distributed in a solution
diffusion
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moves from a high concentration to a low concentration
diffusion
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reaches equilibrium when the concentration is even throughout the solution
diffusion
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describe diffusion
the movement of solute that is unevenly distributed in a a solution
Moves from a high concentration to a low concentration
Reaches equilibrium when the concentration is even throughout the solution
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the movement of water across a semipermeable membrane
osmosis
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the water will move from a low concentration of a solute to a high concentration of a solute
osmosis
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Describe osmosis
- the movement of water across a semipermeable membrane
| - the water will move from a low concentration of a solute to a high concentration of a solute
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Where proteins allow solute to diffuse across a membrane more quickly
facilitated diffusion
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especially useful in the case of charged and polar molecules that have difficulty diffusing across the membrane
facilitated diffusion
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only will work in the direction of diffusion (from high concentration to low)
facilitated diffusion
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Do not require energy from the cel
facilitated diffusion
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channel proteins and carrier proteins
two main type of proteins that allow facilitated diffusion
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The two main type of proteins that allow facilitated diffusion
channel proteins and carrier protein
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provides a corridor for the solute to cross the membrane
channel protein
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channel protein
provides a corridor for the solute to cross the membrane
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Undergoes a conformational change that translocates the solute-binding site across the membrane
carrier protein
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the shape changes maybe triggered by the binding and release of the transported molecule
carrier protein
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carrier protein
- undergoes a conformational change that translocates the solute-binding site across the membrane
- The shape changes maybe triggered by the binding and release of the transported molecule
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Proteins pump soute from one side of the membrane to the other
active transport
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can move solute against a gradient
active transport
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requires energy from the cell usually in the form of ATP
active transport
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active transport
- proteins pump solute from one side of the membrane to the other
- can move solute against a gradient
- requires energy from the cell usually in the form of ATP
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molecules can dissolve in the lipid bilayer and cross it easily
nonpolar molecules
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incluses hydrocarbons, carbon dioxide, and oxygen
nonpolar molecules
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pass only slowly through a lipid membrane
poplar molecules
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includes glucose and other sugars
polar molecules
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even water is slow to travel across the membrane
polar molecules
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Briefly describe how or if ion, polar molecules and non-polar molecules can move across cell membranes
Non-polar molecules can dissolve in the lipid bilayer and cross easily and it involves hydrocarbon, carbon dioxide, and oxygen
- polar molecules pass only slowly through a lipid membrane, even water moves slowly....and includes glucose and sugar,
- charged atoms or molecules (and the surrounding shell of water) have even greater difficulty traveling across a membrane
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the surrounding cell of water have even greater difficulty traveling across a membrane
charged atoms or molecules
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some proteins provide a hydrophobic channel across the membrane that selects for a particular molecule
the role active transport plays in membrane proteins and carbohydrates in the cell
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some proteins shuttle a substance from one side of the membrane to the other by chafing shape
the role active transport plays in membrane proteins and carbohydrates in the cell
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some of these proteins hydrolyze ATP to actively pump substances across the membrane
the role active transport plays in membrane proteins and carbohydrates in the cell
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some enzymes are inserted in the membrane
the role enzyme activity plays in membrane proteins and carbohydrates in the cell
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sometimes associated teams of enzymes associate together in the membrane
the role enzyme activity plays in membrane proteins and carbohydrates in the cell
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chromosomes continue to condense
prometaphase
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briefly describe prophase
```
chromosomes become condensed and visible
spindle fibers emerge from the centromosomes
the mitotic spindle forms
nuclear envelope breaks down
nucleolus disappears
```
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1) Name the three domains of life and briefly describe the characteristics of organisms in that domain.
Eukarya: Includes all eukaryotic cells (cells that have a nucleus and internal membrane-bound compartments)
Archaea: Includes prokaryotic cells that lack peptidoglycan in their cell walls. Members of domain Archaea are more closely related to member of domain Eukarya than they are to members of domain Bacteria.
Bacteria: Includes prokaryotic that have peptidoglycan in their cell walls.
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Name the six kingdoms of life
1. Kingdom Archaebacteria
2. Kingdom Eubacteria
3. Kingdom Protista
4. Kingdom Fungi
5. Kingdom Plantae
6. Kingdom Animalia
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Name the six kingdoms of life. For each kingdom, name the domain that they are in
1. Kingdom Archaebacteria Domain: Archaea
2. Kingdom Eubacteria Domain: Eubacteria
3. Kingdom Protista Domain: Eukarya
4. Kingdom Fungi Domain: Eukarya
5. Kingdom Plantae Domain: Eukarya
6. Kingdom Animalia Domain: Eukarya
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2) Name the six kingdoms of life. For each kingdom, name the domain that they are in, give a brief description of the kingdom and name one organism that is included in that kingdom.
1. Kingdom Archaebacteria Domain: Archaea Description: Includes all members of domain Archaea. Example: All members of domain Archaea are acceptable (for example, Methanobacterium or Haloquadratum)
2. Kingdom Eubacteria Domain: Eubacteria Description: Includes all members of domain Bacteria. Example: All members of domain Bacteria are acceptable (for example, Escherichia coli, Streptococcus, Staphylococcus, etc.)
3. Kingdom Protista Domain: Eukarya Description: Single-celled eukaryotic cells that don’t fit in any other category. Examples: Amoeba, Paramecium, Euglena
4. Kingdom Fungi Domain: Eukarya Description: Single- or multi-cellular eukaryotic cells that have cell walls made of chitin. Examples: Yeast, molds, mushrooms.
5. Kingdom Plantae Domain: Eukarya Description: Multi-cellular eukaryotes that have cell walls made of cellulose and are capable of photosynthesis. Examples: Trees, grass, flowering land plants.
6. Kingdom Animalia Domain: Eukarya Description: Multi-cellular eukaryotes that can’t get their energy from photosynthesis. Examples: Sponges, worms, insects, vertibrates
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3) Briefly describe the characteristics that differentiate prokaryotic and eukaryotic cells.
1. Eukaryotic cells: Have internal membrane-bound compartments, have a nucleus, have 80S (large) ribosomes
2. Prokaryotic cells: Have NO internal membrane-bound compartments, have NO nucleus, have 70S (small) ribosomes
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a. plasma membrane
A bilayer of phospholipids that also contains proteins and carbohydrates. Serves to separate the inside of the cell from the outside of the cell.
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A bilayer of phospholipids that also contains proteins and carbohydrates. Serves to separate the inside of the cell from the outside of the cell.
a. plasma membrane
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b. cell walls (of plants):
A thick layer of cellulose. Protects the cell
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A thick layer of cellulose. Protects the cell
b. cell walls (of plants):
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c. nucleus:
A compartment where the cell’s DNA is stored.
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A compartment where the cell’s DNA is stored.
c. nucleus:
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d. nuclear envelope
: A double lipid membrane that seperates the inside of the nucleus from the cytoplasm. There are large pore proteins that allow molecules to pass from the inside of the nucleus to the outside of the nucleus. The outer layer of the envelope is connected to the ER.
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: A double lipid membrane that seperates the inside of the nucleus from the cytoplasm. There are large pore proteins that allow molecules to pass from the inside of the nucleus to the outside of the nucleus. The outer layer of the envelope is connected to the ER.
d. nuclear envelope
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e. chromatin:
: A structure that consists of molecules of DNA (chromosomes) which is wrapped around proteins (histones). Chromatin can have varying levels of compression.
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A structure that consists of molecules of DNA (chromosomes) which is wrapped around proteins (histones). Chromatin can have varying levels of compression.
e. chromatin:
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f. nucleolus
: A region of the nucleus (not membrane bound) where ribosomal RNA is synthesized
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: A region of the nucleus (not membrane bound) where ribosomal RNA is synthesized
f. nucleolus
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g. ribosomes (free and bound):
Ribosomes are complexes of protein and ribosomal RNA. They consist of a large and a small subunit. They are responsible for the synthesis of proteins from amino acids. Free ribosomes are floating in the cytoplasm and synthesize cytoplasmic proteins. Bound ribosomes are bound to the rough ER and are responsible for synthesizing proteins that are embedded in membranes or are inserted into the lumen of the ER and are destined for transport to other organelles or out of the cell.
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Ribosomes are complexes of protein and ribosomal RNA. They consist of a large and a small subunit. They are responsible for the synthesis of proteins from amino acids. Free ribosomes are floating in the cytoplasm and synthesize cytoplasmic proteins. Bound ribosomes are bound to the rough ER and are responsible for synthesizing proteins that are embedded in membranes or are inserted into the lumen of the ER and are destined for transport to other organelles or out of the cell.
g. ribosomes (free and bound):
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The ER is a large membrane network that stretches throughout the cell. The interior of the ER is called the lumen, the exterior is the cytoplasm. The smooth ER lack bound ribosomes and is responsible for breaking down toxins and synthesizing lipids in some cells.
h. smooth endoplasmic reticulum (ER):
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h. smooth endoplasmic reticulum (ER):
The ER is a large membrane network that stretches throughout the cell. The interior of the ER is called the lumen, the exterior is the cytoplasm. The smooth ER lack bound ribosomes and is responsible for breaking down toxins and synthesizing lipids in some cells.
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: The ER is a large membrane network that stretches throughout the cell. The interior of the ER is called the lumen, the exterior is the cytoplasm. The rough ER has bound ribosomes and is the site where the synthesis of proteins that are embedded in membranes or are inserted into the lumen of the ER and are destined for transport to other organelles or out of the cell occurs.
i. rough endoplasmic reticulum (ER):
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i. rough endoplasmic reticulum (ER):
: The ER is a large membrane network that stretches throughout the cell. The interior of the ER is called the lumen, the exterior is the cytoplasm. The rough ER has bound ribosomes and is the site where the synthesis of proteins that are embedded in membranes or are inserted into the lumen of the ER and are destined for transport to other organelles or out of the cell occurs.
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: A stack of membrane compartments. Has a cis- face and a trans- face. Acts as the shipping and receiving department of the cell. Vesicles are received in the cis- face, their contents sorted in the stacks, and new vesicles are sent out from the trans- face to other compartments, or out of, the cell.
j. golgi apparatus
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j. golgi apparatus
: A stack of membrane compartments. Has a cis- face and a trans- face. Acts as the shipping and receiving department of the cell. Vesicles are received in the cis- face, their contents sorted in the stacks, and new vesicles are sent out from the trans- face to other compartments, or out of, the cell.
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: Vacuoles that contain digestive enzymes and an acidic pH. Merge with food vacuoles to digest them or with other vacuoles to recycle cell components (autophagy).
k. lysosomes
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k. lysosomes
: Vacuoles that contain digestive enzymes and an acidic pH. Merge with food vacuoles to digest them or with other vacuoles to recycle cell components (autophagy).
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Membrane bound compartments that have various uses in the cell. Plant cells have a large central vacuole that animal cells lack
l. vacuoles:
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l. vacuoles:
Membrane bound compartments that have various uses in the cell. Plant cells have a large central vacuole that animal cells lack
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The energy powerhouse of the cell, the site of cellular respiration. Have a double membrane and features that appear to be the remnants of a prokaryotic lifestyle (circular chromosome, small ribosomes). The interior space of the second membrane is termed the mitochondrial matrix.
m. mitochondria
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m. mitochondria
The energy powerhouse of the cell, the site of cellular respiration. Have a double membrane and features that appear to be the remnants of a prokaryotic lifestyle (circular chromosome, small ribosomes). The interior space of the second membrane is termed the mitochondrial matrix.
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The site of photosynthesis in plant cells. Has three membranes, the outer membrane, the inner membrane, and the thylakoid membrane
n. chloroplasts:
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n. chloroplasts:
The site of photosynthesis in plant cells. Has three membranes, the outer membrane, the inner membrane, and the thylakoid membrane
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Protein fibers that gives the cell structure. Three major classes. Microtubules: The thickest fiber, is hollow. Composed of the protein tubulin. Involved in mitosis (the spindle fibers) and flagella/cilia. Microfiliments: The thinnest fiber. Composed of the protein actin. Is involved in giving the cell its shape, amoeboid movement, mitosis (cytokinesis). Intermediate filiments: Several different kinds of fibers, includes lamanin which makes up the nuclear lamina
o. cytoskeleton:
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o. cytoskeleton:
Protein fibers that gives the cell structure. Three major classes. Microtubules: The thickest fiber, is hollow. Composed of the protein tubulin. Involved in mitosis (the spindle fibers) and flagella/cilia. Microfiliments: The thinnest fiber. Composed of the protein actin. Is involved in giving the cell its shape, amoeboid movement, mitosis (cytokinesis). Intermediate filiments: Several different kinds of fibers, includes lamanin which makes up the nuclear lamina
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A pair of rings composed of microtubules. Found in animal cells but not plant cells. Act as the microtubule organizing center of the cell.
centrosome:
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centrosome:
A pair of rings composed of microtubules. Found in animal cells but not plant cells. Act as the microtubule organizing center of the cell.
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5) Name and briefly describe three structures that are possessed by plant cells that are not possessed by animal cells. Name and briefly describe one structure found in animal cells that is not found in plant cells
Plant cells have:
Cell wall: Made of cellulose. Protects the cell.
Central vacuole: Large membrane-bound compartment. Can be used for storage of water or toxins, or other roles in other plants.
Chloroplast: Site of photosynthesis. See question 4 for further description.
Animal cells have;
Centriole: Two small structures composed of microtubules. Act as the microtubule organizing center. See question 4 for furter description.
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6) Briefly describe the fluid mosaic structure of membranes
In the fluid mosaic model, a membrane is a fluid structure with a “mosaic” of various proteins embedded in or attached to a double layer of phospholipids. The proteins and phospholipids are able to move laterally freely, but are unable to change the side of the membrane they are facing.
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7) Briefly describe one role that (each) that membrane proteins and carbohydrates play in the cell.
1.Transport
Some proteins provide a hydrophobic channel across the membrane that selects for a particular molecule
Some proteins shuttle a substance from one side of the membrane to the other by changing shape
Some of these proteins hydrolyze ATP to actively pump substances across the membrane
2.Enzymatic activity
Some enzymes are inserted in the membrane
Sometimes associated teams of enzymes associate together in the membrane
3.Signal transduction
Some membrane proteins (called receptors) bind to specific signaling molecules from outside of the cell
Binding to these molecules causes a shape change in the protein that relays the message into the inside of the cell
4. Cell-cell recognition
Some glycoproteins (proteins and carbohydrates) serve as specific identification tags that are recognized by membrane proteins of other cells
5. Intercellular joining
Some membrane proteins of adjacent cells hook together in various kinds of junctions
Attachment to the cytoskeleton and extracellular matrix (ECM)
Can help stabilize the sell cell and link internal microfilaments to the ECM
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Projections of the cell that have cores of microtubules (9 + 2 arrangement). These microtubules are cross-linked and have motor proteins between them. The movement of the motor proteins causes the cilia to move.
q. cilia:
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q. cilia:
Projections of the cell that have cores of microtubules (9 + 2 arrangement). These microtubules are cross-linked and have motor proteins between them. The movement of the motor proteins causes the cilia to move.
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: Have a similar structure to cilia, but are longer and usually fewer in number.
r. flagella
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r. flagella
: Have a similar structure to cilia, but are longer and usually fewer in number.
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9) Briefly describe diffusion, osmosis, facilitated diffusion, and active transport and give examples of each.
Diffusion: The movement of solute that is unevenly distributed in a solution. Moves from a high concentration to a low concentration. Reaches equilibrium when the concentration is even throughout the solution.
Osmosis: The movement of water across a semipermeable membrane. The water will move from a low concentration of solute to a high concentration of solute.
Facilitated diffusion: Where proteins allow solute to diffuse across a membrane more quickly. Especially useful in the case of charged and polar molecules that have difficulty diffusing across the membrane. Only work in the direction of diffusion (from high concentration to low). Do not require energy from the cell
Two main type of proteins that allow facilitated diffusion
Channel proteins: Provide a corridor for the solute to cross the membrane
Carrier protein: Undergo a conformational change that translocates the solute-binding site across the membrane. The shape changes may be triggered by the binding and release of the transported molecule
Active transport: Proteins pump solute from one side of the membrane to the other. Can move solute against a gradient. Requires energy from the cell (usually in the form of ATP).
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10) Briefly describe the difference between hypotonic, hypertonic, and isotonic solutions. Compare the behavior of plant and animal cells in each of these solutions.
o Hypotonic solution
There is a lower concentration of nonpenetrating solute outside the cell than inside the cell
Water flows into the cell
Causes animal cells to swell and possibly burst
Causes pant cells to swell, but the cell wall prevents them from bursting
• Plant cells in this state are called turgid
• Plant cells are generally healthiest in hypotonic solutions
o Isotonic solution
The concentration of nonpenetrationg solute is the same outside and inside of the cell
The rate of water leaving the cell is the same as the rate of water entering the cell
There is no change in the size or shape of animal cells or plant cells
Animal cells are generally healthiest in isotonic solutions
o Hypertonic solution
There is a higher concentration of nonpenetrating solute outside the cell than inside the cell
Water will flow out of the cell
Animal cells will lose water, shrivel, and possibly die
Plant cells will pull away from the cell wall and possibly burst through plasmolysis
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15) Briefly describe what occurs during the following phases of mitosis: prophase, metaphase, anaphase, and telophase.
• Prophase
o The chromosomes condense, becoming more tightly coiled
Discrete chromosomes are observable with a light microscope.
o Each duplicated chromosome appears as two identical sister chromatids joined together at their centromeres and all along their arms.
o The mitotic spindle begins to form.
The centrosomes start to migrate to opposite poles of the cell. (They are pushed there by lengthening microtubules form the aster.)
• Prometaphase
o The nuclear envelope fragments.
o Microtubules from the asters start to invade the area that was formerly occupied by the nucleus.
o The chromosomes are fully condensed.
o Kinetochores form at the centromere of each chromosome.
o Some of the microtubules attach to the kinetochores.
o Micorotubules that don’t interact with kinetochores (non-kinetochore microtubules) interact with microtubules from the opposite pole of the spindle.
• Metaphase
o The centrosomes are now fully at the opposite poles of the cell
o The chromosomes convene on the metaphase plate .
o For each chromosome, the kinetochores of each sister chromatid are attached to kinetochore microtubules coming from opposite poles.
• Anaphase
o Anaphase starts with the cleavage of the cohesin proteins that are holding the two sister chromatids together.
The two sister chromatids part and are now known as daughter chromosomes.
o The daughter chromosomes start moving toward opposite ends of the cells
Non-kinetochore microtubules from different poles overlap and motor proteins that connect the microtubules start walking them away from one another (using energy from ATP).
This elongates the cell and moves the poles away from each other
o At the end of anaphase, there should be a complete set of chromosomes at each pole of the cell
• Telophase
o Two daughter nuclei start to form in the new cells
o Nuclear envelopes from the parent cell’s nuclear envelope and other portions of the endomembrane system
o Nucleoli reappear
o The chromosomes become less condensed
o Mitosis is now complete
