Unit 11 Flashcards
Define cell
the basic unit of life
What are the components of cell theory?
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells.
Define nucleus
large, membrane-enclosed structure that contains the cell’s genetic material in the form of DNA; it controls many of the cell’s activities
Define eukaryotes
cells that contain nuclei and have membrane-bound organelles
Define prokaryotes
cells that do not contain nuclei and do not have membrane-bound organelles
Define organelles
cell structures that do specialized things
Define cytoplasm
portion of the cell inside the nucleus
Define cell membrane
a flexible barrier that surrounds all cells
Define cell wall
a strong supporting layer around the membrane in plant cells
Define lipid bilayer
a double-layered sheet of lipids
Define concentration
the mass of a solute in a given volume of solution, or mass/volume
Define equilibrium
a state where the concentration of the solute is the same throughout a system
Define isotonic
the concentrations of solutes is the same inside and outside the cell
Define hypertonic
the solution has a HIGHER solute concentration than the cell
*remember: the root “hyper-“ means higher
Define hypotonic
the solution has a LOWER solute concentration than the cell
*remember: the root “hypo-“ means lower
Define passive transport
a type of membrane transport that does not require energy
Define simple diffusion (or diffusion)
the process by which particles move from an area where they are more concentrated to an area where they are less concentrated
Define facilitated diffusion
molecules that cannot diffuse across the cell membrane’s lipid bilayer on their own move through protein channels instead (cell membrane channels facilitate diffusion)
Define osmosis
the diffusion of water through a selectively permeable membrane
Define active transport
an energy-requiring process to move molecules across the cell membrane against their concentration gradient
Define endocytosis
the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane
Define phagocytosis
extensions of cytoplasm surround a particle and package it within a food vacuole, then engulfs it
Define pinocytosis
cells take up liquid from the surround environment, tiny pockets form along the cell membrane, fill with liquid, and pick off to form vacuoles within the cell
Define exocytosis
membrane of the vacuole surrounding the extra material fuses with the cell membrane and forces the contents out of the cell
Define cell division
the process by which a cell divides into two new daughter cells
Define mitosis
first stage of cell division; division of the cell nucleus
Define cytokinesis
division of the cytoplasm
Define chromatids
identical sister pairs which can be put together as a chromosome
Define centromeres
the central attachment point of a pair of chromatids
Define interphase
an “in-between” period of growth
Define cell cycle
a series of events that cells go through as they grow and divide
Define spindle
a fan-like microtubule structure that helps separate the chromosomes
Define nondisjunction
the most common error in meiosis wherein homologous chromosomes fail to separate
Define Barr body
highly condensed X-chromosome
Define X-chromosome inactivation
the turning off of one x chromosome in female cells
Cell membrane: parts and functions
Found in all cells
Thin layer of phospholipids and proteins that separate the cell’s contents from the environment
5-10 mm thick (not important)
Controls transport of substances in and out of the cell
Stabilized by cholesterol and have outward facing heads (hydrophilic), inward facing tails (hydrophobic)
Proteins that help with function
What are three kinds of membrane proteins and what do they do?
Transport proteins: regulate the movement of water soluble molecules through the membrane
Receptor proteins: sets off a cellular response when specific molecules bond to them
Recognition/marker proteins: identify the cell as part of self or as a particular kind of organism
Cytoplasm: parts and functions
Found in all cells
Made of cytosol (semifluid substance made primarily of water and organic compounds)
Contains organelles that perform specialized functions
Cytoskeleton: parts and functions
Found in all cells A network of protein fibers and tubes found throughout the cytoplasm Gives support Roadways Cell transport
Nucleus: parts and functions
Found in plant and animal cells
Contains nearly all the cell’s DNA and with it the coded instructions for making proteins and other important molecules
Surrounded by a double layer of phospholipid called nuclear envelope
Nuclear pores allow mRNA and other materials a way in and out
Nucleolus forms ribosomes
Contains chromatin which can condense into chromosomes
Ribosome: parts and functions
Found in all cells
Proteins are assembled on ribosomes.
Small particles of RNA and protein
Endoplasmic reticulum: parts and functions
Smooth ER
transitional area for transport vesicles
carbohydrate and lipid synthesis
Rough ER
manufactures membranes
synthesizes proteins
Golgi apparatus: parts and functions
Found in plant and animal cells
Modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell
Lysosome: parts and functions
Found in plant and animal cells
Small organelles filled with enzymes that digest lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell
Break down organelles that have outlived their usefulness
Vacuoles: parts and functions
Found in plant and animal cells
Sac-like structures that store materials such as water, salts, proteins, and carbohydrates
Maintains homeostasis through water control and storage
Mitochondria: parts and functions
Contains its own DNA
Convert chemical energy stored in food into compounds that the cell can use
Power-house of the cell
Chloroplasts: parts and functions
Found in plant cells
Organelles that capture energy from sunlight and convert it to chemical energy in photosynthesis
Contains its own DNA
Centriole: parts and functions
Found in animal cells Located near the nucleus Organizes cell division Not found in plant cells Made of tubulin
Cell wall: parts and functions
Found in plant cells
Provides support and protection for the cell
Microfilaments: parts and functions
Threadlike structures made of actin.
Make extensive networks to support the cell and help them move.
They assemble and disassemble to allow for cytoplasmic movement, allowing amoebas to crawl along surfaces.
Microtubules: parts and functions
Hollow structures made out of proteins called tubulins.
Help maintain cell shape and form the mitotic spindle, which is needed in cell division.
Build projections on the surface of the cell called cilia for movement in water
What is found in plant cells?
cell wall, chloroplast, large vacuole
What is found in animal cells?
no cell wall, no chloroplasts, small vacuoles, has centrioles
What is osmosis?
The diffusion of water through a selectively permeable membrane
What are the two problems that all cells that grow large face?
Not enough space in nucleus for transcription (greater DNA demands).
Problems with surface area to volume ratio (difficulty exchanging material)
What happens in the G1 phase?
Cells do most of their growing
Increase in size and make new proteins and organelles
What happens in the S phase?
DNA replication
All chromosomes replicated
Chromosomes consist of 2 sister chromatids in chromatin form now
What happens in the G2 phase?
Second growth phase
Reproduction of some organelles
High microtubule production
Cells grow in size
What happens in the G0 phase?
Usually for non-dividing cells
(muscle, nerve, or senescent cells)
Can occur for cells that are damaged as an alternative to apoptosis
Can be temporary or permanent
Gap phase while in a resting state or performing assigned duties
Order of mitosis
Prophase Metaphase Anaphase Telophase (PMAT) Cytokinesis
What happens in Prophase?
(positioning) Longest phase of mitosis Chromosomes condense Centrioles separate and take up positions on opposite sides of nucleus Nuclear envelope breaks down Mitotic spindles form
What happens in Metaphase?
(middle)
“Tug and pull” of spindle brings the chromatids to the middle of the cell
Each centromere is connected to the two poles of the spindle by microtubules
What happens in Anaphase?
[away]
Chromosomes move to opposite poles
The sister chromatids are pulled away from each other into individual chromosomes
What happens in Telophase?
[two]
Two daughter nuclei form in the cell
Two new nuclear envelopes form
Chromosomes unwind forming chromatin
What happens in Cytokinesis?
The cytoplasm splits
Two daughter cells are created
What are the four functions of the cell membrane?
To isolate the cell cytoplasm from the environment.
To regulate the exchange of essential substances between the cytoplasm and the external environment.
To communicate with other cells.
To identify the cell as belonging to a particular organism.
