AP EXAM 2 Flashcards
What are the 4 general processes carried out by cells?
Cell growth, DNA replication, preparation for division, and cell division
Describe the 3 main components of a cell and their functions.
The cell membrane : surrounds the cell and controls the substances that go into and out of the cell
The nucleus : contains the nucleolus and most of the cells DNA
The cytoplasm : jelly-like fluid inside the cell containing various organelles responsible for different cellular functions
Where are intracellular and extracellular fluids located?
Intracellular is located inside the cells of the body while extracellular fluid is located outside the cells in the spaces between them
Describe the structure of a phospholipid.
Head attracted to water and tail repels water.
How do phospholipids arrange themselves in the plasma membrane? Why?
As a bilayer with heads facing water and tails facing away from water
How is the plasma membrane described according to the fluid mosaic model?
A flexible, fluid mosaic of various components, primarily phospholipids, cholesterol, and proteins, which are embedded within a phospholipid bilayer and can move freely within the membrane plane, allowing for a dynamic and adaptable cell boundary
Describe 5 functions of membrane proteins.
Transporting molecules across the membrane, acting as enzymes, facilitating cell signaling, cell recognition, and anchoring the cell to the extracellular matrix
helps maintain the membranes stucture and fluidity and makes it thicker and less permeable
Cholesterol
cell recognition, cell adhesion, cell signaling, protection, cell membrane stability, energy, blood group determination, immune system assistance
Glycolipids
cell to cell interactions, signaling, immune system, cell shape and integrity, transport, protection
Glycoproteins
channeling or transporting molecules across the membrane
Integral (transmembrane) proteins
support, communication, enzymes, and molecule transfer in the cell
Peripheral proteins
allow the cell to be selectively permeable
Phospholipid bilayer
What is a concentration gradient?
The process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles
Describe the process of diffusion (simple diffusion). Are molecules moving down or against their concentration gradient? Does this movement require energy? Is a protein needed for diffusion to occur in the cell or does it occur across the lipid bilayer? Which type of molecules are more likely to diffuse across the lipid bilayer?
Passive movement of molecules from an area of higher concentration and an area of low concentration, moving DOWN. Occurs directly across the lipid bilayer of a cell membrane, without the need for a protein transporter, allowing small, non-polar, or lipid-soluble molecules to easily diffuse across the membrane, like oxygen and carbon dioxide
Describe factors that can influence the rate of diffusion.
Concentration gradiant, membrane permeability, temperature, and pressure
What is facilitated diffusion? Does this process require a transport or carrier protein? Does this process require energy? Which type of molecules are more likely to utilize facilitated diffusion?
Passive transport where molecules move across a cell membrane with the help of specific transport proteins (carrier proteins or channel proteins), moving DOWN their concentration gradient. Polar molecules and large ions, which cannot easily pass through the cell membrane on their own, are most likely to utilize facilitated diffusion
What are the 3 types of carrier proteins?
Uniporters, symporters, and antiporters
Describe the process of osmosis. What is the difference between osmotic and hydrostatic pressure?
Osmosis is the passive movement of water molecules across a semi-permeable membrane from a region of high water concentration to a region of low water concentration essentially aiming to equalize the solute concentrations on both sides of the membrane.
What is tonicity?
Relative solute concentration of a solution compared to another solution, particularly in relation to a cell; it determines the direction of water movement across a cell membrane
Hypotonic
A solution with a lower solute concentration than the cell, causing water to move into the cell by osmosis leading to the cell SWELLING AND BURSTING
Hypertonic
A solution with a higher solute concentration than the cell, causing the water to move out of the cell by osmosis, leading to cell SHRINKAGE
How does the primary active transport process work?
Uses ATP to move molecules across a membrane by utilizing specific carrier proteins that change shape to bind and transport the desired molecules
What is the main primary active transport pump in our cells? How does it function?
Moves sodium out of cells and potassium into them
How does the process of secondary active transport work?
Harnessing the energy stored in an existing electrochemical gradient, typically active transport, to move a different molecule against its concentration gradient across a cell membrane. SIMPLE: one molecule drags another molecule across the membrane by moving down its own concentration gradient, without directly using ATP
What are two types of endocytosis and how do they differ?
Phagocytosis (cell eating) and Pinocytosis (cell drinking)
What is an endosome?
Membrane-bound vesicle that sorts and transports materials within a cell
Explain the basic process of exocytosis.
Dumps contents outside of the cell. Requires ATP
ATP though a process called oxidative phosphorylation
Mitochondria
single membrane-bound vessicles found in most eukaryotic cells. Cruical for detoxification and lipid metabolism within the cell
Peroxisomes
composed of two subunits, a small and a large on, which function as the site of protein synthesis by translating the genetic code carried by mRNA into a sequences of amino acids to form a polypeptide chain
ribosomes
network of flattened, interconnected membrane sacs STUDDED with ribosomes on its outer surface. The site for protein synthesis, folding, and modification, particularly for proteins destined to be secreted from the cell or embedded in the cell membrane
Rough ER
a network of tubular membranes within a cell, LACKING ribosomes, and functions in the synthesis of lipids, metabolism of carbohydrates, and detoxification of certain substances
smooth er
flattened, stacked membrane sacs. A factory in which proteins are received from the ER are further process and sorted for transport to the eventual destinations: lysosomes, the plasma membrane, or secretion
Golgi Apparatus
Single membrane surrounding a fluid-filled lumen with an acidic pH. Contains enzymes capable of breaking down all types of biological polymers – proteins, nucleic acids, carbohydrates, and lipids
Lysosomes
hollow, cylindrical structures within eukaryotic cells. Involved in mitosis, cell motility, intracellular transport, and maintenance of cell shape
Microtubules
provides mechanical strength and support of cells. Coiled.
Intermediate filaments
flexible, double-stranded helical structures. Provides mechanical support, determines cell shape, and allows movement of the cell surface, thereby enabling cells to migrate, engulf particles, and divide
Actin filaments
What are microvilli and what are their primary functions?
Tiny, finger like projections on the surface of cells significantly increases the cell’s surface area, primarily functions to maximize absorption and secretion of substances
How are cilia and flagella similar? How do they differ?
Cilia are short, hair like structures that cover the surface of some cells in large numbers. Flagella are long, threadlike structures that can only be found at one end of a cell
What are the main components of the nucleus? What is its main function?
Coordinates cell activities like protein synthesis and cell division. Stores and protects the cells DNA and regulating its transcription and replication to control cellular activites. Contains nuclear envelope, nucleoplasm, chromatin, nucleolus.
What is chromatin? How are chromatin and chromosomes related?
Chromatin is a complex of DNA and proteins, primarily histones, that makes up the chromosomes within an eukaryotic cell. Essentially, Chromatin is the “loose” form of DNA that confenses into tightly packed chromosomes during cell division, allowing the long DNA strands to fit inside the nucleus of a cell
What is a nucleolus and what is its function?
The nucleolus is a spherical structure found in the cell’s nucleus whose primary function is to produce and assemble the cell’s ribosomes
Define protein synthesis.
The process by which cells create proteins using amino acids, according to instructions encoded in DNA
Define transcription vs. Translation.
Transcription : genetic information from DNA is copied into a mRNA molecule
Translation: the information in mRNA is used to build a protein by assembling amino acids in a specific sequence based on the mRNA code
What is a nucleotide? What are the 4 nucleotides in DNA (flashback from Chapter 2)
A nucleotide is the basic building block of DNA. The 4 nucleotides are Adenine (A), Thymine (T), Guanine (G), and cytosine (C)
What are the main differences between DNA and RNA?
DNA is double stranded while RNA is single stranded. DNA uses thymine while RNA uses Uracil. DNA contains sugar where RNA contains ribose
Which nucleotides are complementary to one another and so are able to form hydrogen bonds in both DNA and RNA? (Chapter 2)
Adenine and thymine. Cytosin and Guanine.
Describe the basic steps of transcription.
Inititation : RNA polymerase binds to the promoter region on DNA
Elongation: RNA polymerase adds nucleotides to build the RNA strand
Termination : RnA polymerase reaches a terminator sequence and releases the completed RNA molecule from the DNA template
Explain how tRNA acts as the “translator” of the genetic code.
Carrying specific amino acids to the ribosome, where they match up with the corresponding codon on the mRNA molecule, essentially reading the gentic code and ensuring the correct amino acid sequence is incorporated into the growing polypeptide chain during protein synthesis
Describe the basic steps of translation.
Initiation : the ribosome binds to the mRNA and the first tRNA is attached
Elongation : amino acids are added to the growing polypeptide chain by matching tRNA anticodons to mRNA codons
Termination: the completed polypeptide is released when the ribosome reaches a stop codon on the mRNA
Why is post-translational medication necessary for a protein to be functional?
They regulate activity, localization, and interaction with other cellular molecules such as proteins, nucleic acids, lipids, and cofactors
Why is it important to regulate gene expression?
It allows cells to respond to environmental changes, carry out specialized functions based on their cell type, and control the timing and amount of protein production
What does semiconservative replication mean? When does replication occur ding the cell cycle?
Occurs during S phase. When DNA replicates, each new double helix consists of one strand from the original DNA molecule and one newly synthesized strand, essentially conserving half of the original DNA in each new copy
Describe the 3 phases of interphase during the cell cycle.
G1: first gap where the cell grows and prepares for DNA replication
S Phase : DNA is replicated
G2 : Gap 2, where the cell further grows and prepares for mitosis by synthesizing proteins needed for cell division
the chromosome condense and centrosomes move to opposite sides of the nucleus, initiating formation of the mitotic spindle
prophase
the nucleus dissolves and the cell’s chromosomes condense and move together, aligning in the center of the dividing cell
metaphase
separation of replicated chromosomes at the centromere, which are then actively pulled apart by the spindle fibers towards opposites poles of the cell. Each pair of chromosomes is separated into two identical, independent chromosomes
anaphase
Chromosomes that have migrated to opposite poles of the cell begin to uncoil and decondense, a new nuclear membrane forms around each set of chromosomes, the nucleoli reappear, and the mitotic spindle disassembles.
telophase
What is cytokinesis?
The cytoplasmic division of a cell at the end of mitosis, bringing about the separation into two daughter cells
What are four external factors that play a role in cell cycle control?
Growth factors, nutrient availability, cell to cell contact, and environmental cues like temperature and pH levels
