Module 3: Cells Flashcards
The cell can be divided into three principal parts
Plasma (cell) membrane
Cytoplasm:
Cytosol Organelles (except for the nucleus)
Nucleus
a flexible, sturdy barrier that contains the cell cytoplasm
plasma membrane
describe the structure of the plasma membrane
composed of a double layer (bilayer) of phospholipid molecules with many protein molecules dispersed within it.
Which parts of the plasma membrane are hydrophillic vs hydrophobic
The surfaces of the membrane are hydrophilic due to the polar phosphate heads. The internal portion of the membrane is hydrophobic due to the nonpolar fatty acid tails
Integral proteins are firmly inserted into and extend across the lipid bilayer of the Plasma Membrane. Most of these proteins are glycoproteins
Most of these proteins are glycoproteins, which serve as channels (pores), transporters (carriers), receptors (recognition sites), or enzymes
Plasma membranes are what level of permeability
Plasma membranes are selectively permeable, meaning that some things can pass through and others cannot.
The lipid bilayer portion of the membrane is permeable to what and impermeable to what
The lipid bilayer portion of the membrane is permeable to small, nonpolar, uncharged molecules, but impermeable to ions and charged or polar molecules. This bilayer also is permeable to water.
Transmembrane proteins
act as channels or transporters increase the permeability of the membrane to molecules that cannot cross the lipid bilayer
Macromolecules pass through the plasma membrane by
vesicular transport
Intracellular fluid (ICF) is located
inside the cell
extracellular fluid (ECF) is located
outside the cell.
The types of extracellular fluid
Interstitial fluid
Plasma
Lymph
Solutes
substances dissolved in a solvent.
concentration gradient
the difference in the concentrations of a substance between two areas (e.g., the amount of water in your cells compared to the amount of water in the lake in which you are swimming, or the amount of sodium ions in extracellular fluid compared to the amount of sodium ions in intracellular fluid)
Vesicular transport involves
the formation of membrane-surrounded vesicles to move materials into or out of the cell by endocytosis or exocytosis.
Living cells use three passive transport processes
non-mediated (diffusion through the lipid bilayer and diffusion through a channel)
mediated (facilitated diffusion).
the random mixing of particles that occurs in a solution as a result of the kinetic energy of the particles
Diffusion
the random mixing of particles that occurs in a solution as a result of the kinetic energy of the particles
Diffusion
Diffusion is influenced by
Steepness of the concentration gradient
Temperature
Size or mass of the diffusing substance
Surface area
Diffusion distance
Movement of molecules or ions down a concentration gradient means
Movement from a region of high concentration towards region of low concentration
Most membrane channels are ion channels, allow
the passage of small, inorganic, hydrophilic ions
a solute binds to a specific transporter on one side of the membrane and is released on the other side after the transporter undergoes a conformational change
facilitated diffusion
This is the process by which glucose enters and leaves most human cells
facilitated diffusion
the diffusion of water molecules through a selectively permeable membrane. It is the movement of water (the solute) from an area of higher concentration to an area of lower concentration across the membrane.
osmosis
relates to the concentration of solutes outside of the cell relative to the inside of a cell, and how the solution influences the shape of body cells.
tonicity
the concentration of solutes outside of the cell is the same as that inside the cell. In such a solution, red blood cells maintain their normal shape.
isotonic solution
the concentration of solutes outside of the cell is less than that inside the cell. In such a solution red blood cells swell, and undergo hemolysis.
hypotonic solution,
the concentration of solutes outside of the cell is greater than that inside the cell. In such a solution, red blood cells shrink and undergo crenation.
hypertonic solution
an energy-requiring process that moves solutes such as ions, amino acids, and monosaccharides against a concentration gradient.
Active transport
an energy-requiring process that moves solutes such as ions, amino acids, and monosaccharides against a concentration gradient.
Active transport
molecules or particles that are too large to enter the cell by diffusion or active transport are brought into a vesicle formed from a section of the cell membrane.
endocytosis
molecules or particles that are too large to enter the cell by diffusion or active transport are brought into a vesicle formed from a section of the cell membrane.
endocytosis
, membrane-enclosed structures called secretory vesicles, which form inside the cell, fuse with the cell membrane and release their contents into the extracellular fluid.
exocytosis,
a small membranous sac that forms by budding off from a cell membrane.
vesicle
Two types of vesicular transport are:
Endocytosis
Exocytosis
The three main types of endocytosis are:
Phagocytosis
Pinocytosis (bulk-phase endocytosis)
Receptor-mediated endocytosis
the intracellular fluid, is the semifluid portion of cytoplasm that contains inclusions and dissolved solutes
Cytosol
Cytosol is composed mostly of
water, plus proteins, carbohydrates, lipids, and inorganic substances.
network of several kinds of protein filaments that extend throughout the cytoplasm and provide a structural framework for the cell.
cytoskeleton
cytoskeleton consists of
microfilaments, intermediate filaments, and microtubules.
Most microfilaments are composed of
actin, and function in movement and mechanical support.
composed of several different proteins, and function in support and helping to anchor organelles such as the nucleus.
Intermediate filaments
Microtubules are composed of a protein called tubulin, and help determine
cell shape and function in the intracellular transport of organelles and the migration of chromosomes during cell division.
Centrosomes are dense areas of cytoplasm that contain the
centrioles
the paired cylinders arranged at right angles to one another—that serve as centres for organizing microtubules in interphase cells and the mitotic spindle during cell division.
centrioles
numerous, short, hair-like projections extending from the surface of a cell, which function to move materials over the surface of cells located in the lining of the respiratory tract and fallopian tubes.
Cilia
similar to cilia but are much longer; usually, they move an entire cell. The only example of one in the human body is the tail of the sperm cell.
Flagella
tiny spheres that consist of ribosomal RNA and several ribosomal proteins; they occur free (singly or in clusters) or together with endoplasmic reticulum.
Ribosomes
a network of membranes that form flattened sacs or tubules called cisterns.
endoplasmic reticulum (ER
continuous with the nuclear membrane and has an outer surface studded with ribosomes.
Rough ER
extends from the rough ER to form a network of membrane tubules, but it does not contain ribosomes on its membrane surface
Smooth ER
transports substances, stores newly synthesized molecules, synthesizes and packages molecules, detoxifies chemicals, and releases the calcium ions involved in muscle contraction.
The endoplasmic reticulum
consists of four-to-six stacked, flattened membranous sacs (cisterns) referred to as cis, medial, and trans. The principal function of the Golgi complex is to process, sort, and deliver proteins and lipids to the plasma membrane, lysosomes, and secretory vesicles.
Golgi complex
membrane-enclosed vesicles that form in the Golgi complex, and which contain powerful digestive enzymes. Lysosomes function in intracellular digestion, the digestion of worn-out organelles (autophagy), the digestion of cellular contents (autolysis) during embryological development, and extracellular digestion.
Lysosomes
digestion of worn-out organelles
autophagy
the digestion of cellular contents
(autolysis)
similar in structure to, but are smaller than, lysosomes. contain enzymes (e.g., catalase) that use molecular oxygen to oxidize various organic substances.
Peroxisomes
a tiny membrane-bound sac that contains protease enzymes, which are able to cut proteins
A proteasome
bound by a double membrane. The outer membrane is smooth, whereas the inner membrane is arranged in folds called cristae.
The mitochondrion
the site of ATP production in the cell through the catabolism of nutrient molecules.
Mitochondria
Mitochondria self-replicate using
their own DNA.
includes the nuclear envelope—which is perforated by channels called nuclear pores—the nucleoli, and genetic material (DNA)
The nucleus
a long molecule of DNA that is coiled together with several proteins. Human somatic cells have 46 of these arranged in 23 pairs.
chromosome
The various levels of DNA packaging
represented by nucleosomes, chromatin fibres, loops, chromatids, and chromosomes.
the process by which the genetic information encoded in DNA is copied onto a strand of RNA called messenger RNA (mRNA), which directs the protein synthesis. Besides serving as the template for the synthesis of mRNA, DNA also synthesizes two other kinds of RNA—ribosomal RNA (rRNA) and transfer RNA (tRNA).
Transcription
the process of reading the mRNA nucleotide sequence to determine the amino acid sequence of the protein.
Translation
the process by which cells reproduce themselves. It consists of nuclear division (mitosis and meiosis) and cytoplasmic division (cytokinesis).
Cell division
The stages of mitosis
prophase, metaphase, anaphase, and telophase
the distribution of two sets of chromosomes, one set into each of two separate nuclei.
Mitosis
Name the three principal parts of a generalized cell
Plasma membrane, Cytoplasm, Nucleus
State the difference between integral and peripheral membrane proteins
Integral proteins penetrate through the membrane; peripheral proteins are on the inner or outer surface.
Name the two types (categories) of membrane proteins
Integral and peripheral
List three functions of the cell membrane:
Channel Transporter Receptor Enzymes Anchor Identify marker
The fluid inside a cell is called the
intracellular fluid
while the fluid outside the cell is called the
extracellular fluid
Define the terms passive with respect to membrane transport.
Passive transport involves movement from a region of high concentration to a region of low concentration without an expenditure of energy.
Define the terms active with respect to membrane transport.
Active transport involves the movement of materials against a concentration gradient with the use of energy.
osmosis.
Osmosis is the diffusion of water through a selectively permeable membrane from a region of high water concentration to a region of lower water concentration
Define the term hypotonic
In a hypotonic solution, a lower concentration of solutes and a higher concentration of water occurs
Define the term hypertonic.
a hypertonic solution has a higher concentration of solutes and a lower concentration of water.
Describe the cytosol of the cell
The cytosol of the cell is the viscous fluid within which the organelles and inclusions are suspended. It is the site of most intracellular chemical reactions.
Describe the structure of the nucleus.
The nucleus is a spherical structure surrounded by a double membrane, and contains the nucleolus and chromatin.
Describe the structure and location of the ribosomes.
Ribosomes are small globular granules (about 25 nm across) made of ribosomal RNA and protein. They are found free in the cytoplasm or attached to the endoplasmic reticulum.
Identify the function of the lysosomes.
Lysosomes contain digestive enzymes used by cells to reprocess intracellular materials such as cell membranes, and extracellular materials such as bone
What is the function of the microtubules?
Microtubules provide shape and structural support for cells. They also provide the mechanism for the movement of cilia and flagella, and for the movement of chromosomes during mitosis
Identify the primary function of cilia.
Cilia cause the movement of materials such as mucous across cell surfaces.
What is the cytoskeleton?
The cytoskeleton is a framework within the cell; its function is related mainly to movement and support. It is made up of microtubules, microfilaments, and intermediate filaments.
The cytoskeleton proteins with the smallest diameter are called
microfilaments
Define the terms transcription and translation.
Transcription is the copying of a base sequence of DNA into a base sequence of RNA. Translation is the use of a base sequence of messenger RNA to assemble a corresponding sequence of amino acids.
Fill in the appropriate RNA nucleotide that would be expected to pair with the DNA nucleotide shown below:
C–T–T–A–G–A–G–A–T—G
G–A–A–U–C–U–C–U–A–C
The process of transcription provides which three types of RNA?
Messenger RNA
Transfer RNA
Ribosomal RNA
What is the anticodon?
The anticodon is a sequence of three nucleotides on a transfer RNA molecule, which allows the t-RNA to bind to a specific sequence of three nucleotides on the messenger RNA.
What is a termination (stop) codon?
A termination codon is a three-nucleotide sequence in messenger RNA that signifies the end of the message.
What is a gene? What is its function?
A gene is a specific sequence of nucleotides in DNA that determines the amino acid sequence of a protein
For successful somatic cell division to occur, the cell must undergo mitosis followed by cytokinesis. Explain these two terms.
Division of the nucleus
Division of the cytoplasm (cytokinesis)
A cell spends most of its life in what stage of the life cycle?
Interphase
The cellular contents located between the outer limiting membrane of a cell and its nucleus are collectively known as:
Cytoplasm
Which lipids compose approximately three-fourths of the lipids in the plasma membrane of a human cell?
Phospholipids
Which cell organelle is the site of fatty acid, phospholipid, and steroid synthesis?
Smooth endoplasmic reticulum
Which cell organelle is the site of fatty acid, phospholipid, and steroid synthesis?
Smooth endoplasmic reticulum
Human cells are basically factories that produce large numbers of diverse
Proteins
The only example of a flagellum in the human body is in the:
Tail of a sperm cell.
