Lesson 2 Cell Biology Flashcards
What is the basic unit of life?
The cell.
What are the general parts of a cell?
- Plasma (cell) membrane
- Nucleus
- Cytoplasm
What is the function of the plasma (cell) membrane?
Allows cell interaction with its external environment.
What does the nucleus do?
Directs cell activities.
What is cytoplasm?
Located between plasma membrane and nucleus; contains organelles.
What does cell metabolism include?
All chemical reactions that occur in the cell, often involving energy transfer.
What types of molecules do cells synthesize?
- Proteins
- Nucleic acids
- Lipids
How do cells communicate?
Cells produce and receive electrical and chemical signals.
What is the role of DNA in cells?
Contains a complete copy of all genetic information for the individual.
What type of microscope has a resolution of about 0.1µm?
Light microscope.
What is the resolution of an electron microscope?
About 0.1nm.
What are the functions of the plasma membrane?
- Separates intracellular from extracellular substances
- Encloses and supports cell contents
- Attaches to the extracellular environment or other cells
- Recognizes and communicates with other cells
- Determines what moves in and out of cells
What is membrane potential?
An electrical charge difference across the plasma membrane.
What predominates in membrane lipids?
- Phospholipids
- Cholesterol
What is the structure of phospholipids in the membrane?
Bilayer with polar heads facing water and nonpolar tails facing each other.
What is the role of cholesterol in the plasma membrane?
Determines fluid nature and provides stability.
What is the glycocalyx?
Combinations of carbohydrates and lipids (glycolipids) and proteins (glycoproteins) on the outer surface.
What are integral membrane proteins?
Proteins that extend deeply into the membrane and can form channels.
What are peripheral membrane proteins?
Attached to integral proteins or to polar heads of phospholipids.
What are marker molecules?
Glycoproteins or glycolipids that allow cells to identify one another.
What are cadherins?
Integral proteins that attach cells to other cells.
What is the main cause of autoimmune blistering diseases?
Autoantibody-mediated attacks on cadherin-associated adhesion complexes.
What do transport proteins include?
- Channel proteins
- Carrier proteins
- ATP-powered pumps
What are leak ion channels?
Always open and responsible for the permeability of the plasma membrane to ions.
What is cystic fibrosis caused by?
Mutations in the CFTR gene affecting chloride ion channels.
What do local anesthetics like lidocaine block?
Voltage-gated Na⁺ channels.
What is the function of GLUT4?
Helps absorb glucose from the blood in response to insulin.
What does ATP-powered pumps require?
The breakdown of ATP.
What is the function of LDL receptors?
Bind and remove low-density lipoprotein (LDL) from circulation.
What is osmolarity?
A measure of how concentrated a solution is, indicating the number of particles dissolved in liquid.
What is the normal range of human body fluid osmolarity?
275–295 mOsm/Litre.
What is passive membrane transport?
Movement from higher concentration to lower concentration without ATP.
What is osmosis?
Diffusion of water across a selectively permeable membrane.
What are aquaporins?
Water channel proteins.
What factors affect the rate of simple diffusion?
- Magnitude of concentration gradient
- Temperature of solution
- Size of diffusing molecules
- Viscosity of solvent
What is facilitated diffusion?
Passive transport of solutes across the plasma membrane with the assistance of transporters.
What is the difference between symporters and antiporters?
- Symporters move two ions/molecules in the same direction
- Antiporters move two ions/molecules in opposite directions
What is osmolarity?
Way to measure how concentrated a solution is; tells us how many tiny particles are dissolved in a certain amount of liquid.
What does a value outside the normal osmolarity range indicate?
Can indicate dehydration, overhydration, or other medical conditions.
Define isosmotic solutions.
Solutions with the same concentrations of solute particles; equal osmotic pressures.
What is a hyperosmotic solution?
Solution with a greater concentration of solute; has a greater osmotic pressure.
What is a hypoosmotic solution?
Solution with a lesser concentration of solute; has a lesser osmotic pressure.
What happens to a cell in an isotonic solution?
Cell neither shrinks nor swells.
What occurs to a cell in a hypertonic solution?
Cell shrinks (crenation) as water moves out of the cell.
What happens to a cell in a hypotonic solution?
Cell swells and may rupture (lysis) as water moves into the cell.
What is facilitated diffusion?
Mediated transport process carried out by carrier/channel proteins; no ATP required.
What types of molecules are moved by facilitated diffusion?
Large, water-soluble molecules or electrically charged molecules.
What is the role of the sodium-potassium pump?
Moves sodium ions out of the cell and potassium ions into the cell, creating electrical potentials across membranes.
What does active transport require?
Requires ATP.
Define secondary active transport.
Use of potential energy in concentration gradient of one substance to help move another substance.
List the types of vesicular transport.
- Endocytosis
- Exocytosis
- Phagocytosis
- Pinocytosis
- Transcytosis
What is receptor-mediated endocytosis?
Specific molecules in the extracellular fluid bind to receptors in the plasma membrane, forming a vesicle.
What is the function of lysosomes?
Digest cellular material, including nutrients and phagocytized bacteria.
What is Tay-Sachs disease?
A rare genetic disorder caused by the inability of lysosomal enzymes to break down gangliosides, leading to cell damage.
What is the primary role of ribosomes?
Sites of protein synthesis.
What are the two types of endoplasmic reticulum?
- Rough ER
- Smooth ER
What does the rough endoplasmic reticulum do?
Has attached ribosomes; where proteins are produced and modified.
What is the function of the Golgi apparatus?
Modifies, packages, and distributes proteins and lipids for secretion or internal use.
What happens to proteins produced at the ribosomes attached to the rough ER?
They are packed into transport vesicles and moved to the Golgi apparatus.
What type of proteins do free ribosomes synthesize?
Proteins used inside the cell.
What is the role of peroxisomes?
Contain enzymes to break down fatty acids and amino acids; also detoxify hydrogen peroxide.
What is the structure of chromosomes?
DNA associated with proteins called histones to form nucleosomes.
Describe the nucleus.
Large membrane-bound structure containing DNA, surrounded by a nuclear envelope with nuclear pores.
What is the nucleolus?
Dense region within the nucleus where ribosomes are manufactured.
What causes progeria?
A mutation in the LMNA gene affecting the nuclear envelope, leading to unstable cell nuclei.
What is the function of the cytoskeleton?
Supports the cell and allows for movements like changes in cell shape.
Fill in the blank: The _______ is the fluid portion of the cytoplasm.
cytosol
What are the primary symptoms of Tay-Sachs disease?
Paralysis, blindness, and death, usually before age 5
Damage to the central nervous system begins in the fetus, with symptoms appearing several months after birth.
What causes Tay-Sachs disease?
Deficiency of the enzyme hexosaminidase A in the lysosome
This enzyme is responsible for breaking down GM2 ganglioside, leading to its accumulation and neurodegeneration.
What is the typical age of death for individuals with Tay-Sachs disease?
Usually by age 4 or 5
What is a common method to reduce the incidence of Tay-Sachs disease?
Genetic counseling accompanied by prenatal screening
What is the role of proteasomes in cells?
Break down and recycle proteins
Proteasomes consist of large protein complexes that form a barrel-like structure.
Which neurodegenerative disease is commonly linked to proteasomal dysfunction?
Parkinson’s disease
What is the hallmark protein accumulation in Parkinson’s disease?
Alpha-synuclein
What is the primary function of mitochondria?
Major site of ATP synthesis
What is Leber’s Hereditary Optic Neuropathy (LHON)?
A mitochondrial genetic disorder causing sudden vision loss
What causes LHON?
Mutations in mitochondrial DNA that affect complex I of the mitochondrial respiratory chain
What structure do centrioles form part of?
Centrosome
What role do centrioles play in cell division?
Organize microtubules called spindle fibers
What disorder is linked to defects in cilia structure or function?
Primary Ciliary Dyskinesia (PCD)
What autoimmune disorder is associated with damaged microvilli?
Celiac disease
What are genes?
Functional units of heredity
What is gene expression?
The production of RNA and/or proteins from the information stored in DNA
What are the two steps involved in gene expression?
Transcription and translation
What occurs during transcription?
Information from DNA is used to produce mRNA
What are introns?
Regions of the gene that are not part of the code for a protein
What is alternative splicing?
Joining various combinations of exons into mRNA to produce different proteins from the same gene
What is the genetic code?
Information contained in mRNA that relates the nucleotide sequence to the amino acid sequence of a protein
What are codons?
Three nucleotide sequences in mRNA that specify amino acids during translation
What is the start codon?
AUG, which codes for methionine
What is the function of tRNA during translation?
Carries specific amino acids to the ribosomes
What is a polyribosome?
A cluster of ribosomes attached to the same mRNA
What is posttranslational protein processing?
The modification of proteins after their synthesis
What occurs during the G1 phase of interphase?
Cells carry out normal activities and increase in size
What is the role of DNA polymerase?
Catalyzes DNA synthesis during replication
What is the difference between diploid and haploid number of chromosomes?
Diploid has two sets of chromosomes; haploid has one set
What is the function of spliceosomes?
Remove introns from pre-mRNA
What is the role of a poly-A tail in mRNA?
Ensures mRNA travels from the nucleus to the cytoplasm
What occurs during DNA replication?
The strands of DNA separate, old strands serve as templates for new strands, resulting in two identical DNA molecules
DNA synthesis is catalyzed by DNA polymerase.
What is the role of DNA ligase in DNA replication?
DNA ligase splices Okazaki fragments together
This is essential for the completion of the lagging strand.
What type of chromosome number do somatic cells have?
Diploid
Somatic cells contain two sets of chromosomes.
What type of chromosome number do sex cells have?
Haploid
Sex cells contain one set of chromosomes.
What happens to chromatin during mitosis?
Chromatin condenses to form chromatids, which are joined at the centromere
This forms a single chromosome.
Name the phases of mitosis in order.
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
Cytokinesis is a separate process that follows mitosis.
What is apoptosis?
Programmed cell death to maintain normal cell numbers and remove excess or potentially dangerous cells
It is regulated by specific genes.
List some hypotheses regarding how aging occurs.
- Cellular clock
- Death genes
- DNA damage
- Free radicals
- Mitochondrial damage
These hypotheses explore different mechanisms of cellular aging.
What is the structure of the plasma membrane?
Consists of a phospholipid bilayer with embedded proteins
The bilayer has hydrophilic heads and hydrophobic tails.
What is the function of the nucleus in a cell?
Contains the cell’s genetic information, determining its structure and function
It directs the cell’s activities.
What are the two types of organelles found in a cell?
- Non-membranous organelles
- Membranous organelles
Examples include ribosomes (non-membranous) and mitochondria (membranous).
What is facilitated diffusion?
The process where molecules pass through a membrane via a carrier protein
This process does not require energy.
What does the sodium-potassium pump do?
Transports sodium ions out of the cell and potassium ions into the cell
This process requires energy (ATP).
What is the effect of a hypotonic solution on red blood cells?
Causes water to enter the cell, leading to swelling or bursting
This is due to osmosis.
What is osmotic pressure?
The pressure required to prevent the flow of water across a selectively permeable membrane
It is influenced by solute concentration.
True or False: Cytokinesis is part of mitosis.
False
Cytokinesis is a separate process that occurs after mitosis.
What are the extensions of the plasma membrane called?
- Microvilli
- Cilia
- Flagellum
These structures increase surface area or assist in movement.
Fill in the blank: The process of programmed cell death is known as _______.
apoptosis
What is the primary function of ribosomes?
Protein synthesis
Ribosomes can be free in the cytoplasm or bound to the endoplasmic reticulum.
What is the function of the nucleus in a cell?
The nucleus contains the cell’s genetic material and controls cellular activities
The nucleus is often referred to as the control center of the cell.
What structures are found within the nucleus?
The structures found within the nucleus include:
* Nucleolus
* Chromatin
* Nuclear envelope
* Nuclear pores
What are the main components of the nuclear envelope?
The nuclear envelope consists of:
* Outer membrane
* Inner membrane
* Nuclear pores
What is the role of the Golgi apparatus?
The Golgi apparatus modifies, sorts, and packages proteins for secretion or use within the cell.
Fill in the blank: Proteins are produced at the _______.
rough endoplasmic reticulum
During which phase does DNA replication occur in the cell cycle?
S phase
What are the phases of the cell cycle?
The phases of the cell cycle include:
* G1 phase
* S phase
* G2 phase
* M phase (mitosis)
What happens during cytokinesis?
Cytokinesis is the process where the cytoplasm divides, forming two new cells.
List the stages of mitosis in order.
The stages of mitosis are:
* Prophase
* Prometaphase
* Metaphase
* Anaphase
* Telophase
What is the role of the nucleolus?
The nucleolus is responsible for the production of ribosomes.
True or False: The G0 phase occurs after the G1 phase.
True
What occurs during the prophase stage of mitosis?
During prophase, chromosomes thicken and shorten to form chromatids, and the spindle fibers begin to form.
What is a splice in mRNA processing?
A splice refers to the joining of exons after introns are removed during mRNA processing.
What are the components of pre-mRNA?
Pre-mRNA consists of:
* Exon 1
* Intron
* Exon 2
What happens to proteins after they are modified by the Golgi apparatus?
Modified proteins can be released from the Golgi apparatus or used within the cell.
Fill in the blank: The _______ phase is also known as the first gap phase.
G1
What is the function of ribosomes on the rough endoplasmic reticulum?
Ribosomes synthesize proteins during translation.
What marks the end of the M phase in the cell cycle?
Cytokinesis marks the end of the M phase.
