Module 3: Cells Flashcards
What is a cell?
The smallest structural unit of all living organisms that is capable of functioning independently.
What are the 3 main parts the cell is divided into?
The plasma membrane, the cytoplasm, and the nucleus
Describe the structure of the plasma membrane?
Surrounds and contains the cytoplasm of a cell. Consists mostly of phospholipids, arranged in a bilayer and proteins most of which are glycoproteins.
Describe the structure of the cytoplasm?
Includes all the cellular contents between the plasma membrane and nucleus. Cytosol and organelles
Describe the structure of the nucleus?
Consists of a double nuclear envelope; nuclear pores, which control the movement of substances between the nucleus and cytoplasm, nucleoli, which produces ribosomes; and genes arranged on chromosomes.
What are the functions of the plasma membrane?
Acts as a barrier separating inside and outside of the cell. Controls the flow of substances into and out of the cell. Helps identify the cell to other cells (immune cells). Participates in intercellular signaling.
Describe simple diffusion: lipid-soluble molecules diffuse through the lipid bilayer.
In simple diffusion there is a net (greater) movement of substances from a region of their high concentration to a region of their lower concentration.
Describe facilitated diffusion
An integral membrane protein assists a specific substance to move across the membrane. The membrane protein can either form channels or function as carriers.
What is osmosis?
Osmosis is the net movement of water molecules through a selectively permeable membrane.
What is an isotonic solution?
One which cells maintain their normal shape and volume.
What happens in a hypotonic solution?
Molecules enter the cells by osmosis faster than they leave which causes the cells to swell and eventually burst which is called hemolysis.
What happens in a hypertonic solution?
Water molecules move out of the cells by osmosis faster than they enter causing the cells to shrink and shrivel up. This is called crenation.
Explain the function of the sodium potassium pump
Na+ ions are expelled from the cell and K+ ions are imported into the cell. The pump does not work unless Na+ and ATP are present in the cytosol and K+ Is present in the extracellular fluid. The sodium potassium pump maintains a low intracellular concentration of Na+
___ is a vital defense mechanism that helps protect the body from disease.
Phagocytosis
Movement of substances down a concentration gradient until equilibrium is reached; do not require cellular energy in the form of ATP is __ __
Passive processes
Movement of a substance by kinetic energy down a concentration gradient until equilibrium is reached is ___
Diffusion
Passive movement of a substance through the lipid bilayer of the plasma membrane is __ __
Simple diffusion
Ex: lipid soluble molecules oxygen, carbon dioxide, nitrogenous gases, fatty acids, steroids, fat-soluble vitamins A D E K, polar molecules like water and urea
Passive movement of a substance down its concentration gradient aided by ion channels and carriers is __ __
Facilitated diffusion
Ex: K+, Cl-, Na+, Ca2+, glucose, fructose, galactose and some vitamins
Movement of water molecules across a selectively permeable membrane from an area of higher concentration to an area of lower water concentration is ___
Osmosis
Movement of substances against a concentration gradient; requires cellular energy in the form of ATP is __ ___
Active processes
Transport in which a cell expends energy to move a substance across the membrane against its concentration gradient aided by membrane proteins that act as pumps; these integral membrane proteins use energy supplies by ATP ___ ___
Active transport
Ex: Na+, K+, Ca2+, H+, I-, Cl- AND other ions
Movement of substances into or out of a cell in vesicles that bud from the plasma membrane; requires energy supplies by ATP are __ __
Transport vesicles
Movement of substances into a cell in vesicles ___
Endocytosis
Cell eating; movement of a solid particle into a cell after pseudopods engulf it.
Phagocytosis
Ex: bacteria, viruses, and aged or dead cells
Cell drinking; movement of extracellular fluid into a cell by infolding of plasma membrane.
Bulk-phase endocytosis (pinocytosis)
Ex: solutes in extracellular fluid
Movement of substances out of a cell in secretory vesicles that fuse with the plasma membrane and release their contents into the extracellular fluid.
Exocytosis
Ex: neurotransmitters, hormones, and digestive enzymes
Describe the structure of the cytoskeleton?
Extending throughout the cytosol, the cytoskeleton is a network of three kinds of protein filaments: microfilaments, intermediate filaments and microtubules.
Describe the functions of the cytoskeleton.
Serves as a scaffold that helps to determine a cells shape and to organize the cellular contents. Aids movement of organelles within the cell of chromosomes during cell division, and of whole cells such as phagocytes.
What is the centrosome?
The pericentriolar material of a centrosome organizes the mitotic spindle during cell division.
Describe the functions of the centrosomes.
The pericentriolar matrix of the centrosome contains tubulins that build microtubules in non dividing cells and form the mitotic spindle during cell division.
What are ribosomes?
The sites of protein synthesis, consist of a large subunit and a small subunit.
Describe the functions of ribosomes.
Ribosomes associated with endoplasmic reticulum synthesize proteins destined for insertion in the plasma membrane or secretion from the cell. Free ribosomes synthesize proteins used in the cytosol.
Describe the structure of the endoplasmic reticulum (ER)?
The ER is a network of folded membranes that extend throughout the cytoplasm and connect to the nuclear envelope.
Describe the functions of the endoplasmic reticulum (ER).
Rough ER synthesize glycoproteins and phospholipids that are transferred into cellular organelles, inserted into the plasma membrane, or secreted during exocytosis. Smooth ER synthesis fatty acids, steroids, such as estrogens and testosterone; inactivates or detoxifies drugs and other potentially harmful substances; removes the phosphate group from glucose 6 phosphate; and stored and releases calcium ions that trigger contraction in muscle cells.
What is the Golgi complex?
“A processing plant”. Most proteins synthesized by ribosomes attached to rough ER pass through the Golgi complex for processing.
What are the functions of the Golgi complex?
Modifies, sorts, packages, and transports proteins received from the rough ER. Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid; forms membrane vesicles that ferry new molecules to other organelles such as lysosomes.
What is the 7e7374473737373mitochondrion?
Within mitochondria, chemical reactions generate most of a cells ATP.777e77e7e
What is the function of mitochondria?
Generate ATP through reactions of aerobic cellular respiration. Within mitochondria, chemical reactions generate most of a cells ATP.
What is the nucleus?
The nucleus contains most of a cells genes, which are located on chromosomes.
Where does transcription and translation take place?
Transcription occurs in the nucleus; translation takes place in the cytoplasm.
Describe messenger RNA (mRNA).
Directs synthesis of a protein.
Describe ribosomal RNA (rRNA).
Joins with ribosomal proteins to make ribosomes.
Describe transfer RNA (tRNA).
Binds to an amino acid and holds it in place on a ribosome until it is incorporated into a protein during translation. Each of more than 20 different types of tRNA binds to only one of the 20 different amino acids.
What happens in transcription in the nucleus?
During transcription, the genetic information is copied to RNA.
Describe protein elongation and termination of protein synthesis during translation in the cytoplasm.
During protein synthesis the ribosomal subunits join, but they separate when the process is complete.
What are the 4 phases of cellular division?
Prophase, metaphase, anaphase, telophase.
What is reproductive cell division (meiosis)?
The process that produces gametes - sperm and oocytes.
What is somatic cell division?
A single cell divides to produce 2 identical cells.
