Biology slides 3
What is the basic unit of life?
The cell.
What types of organisms consist of cells?
Both unicellular and multicellular organisms.
What surrounds a cell and distinguishes it from its environment?
The cell membrane.
What genetic material do all cells contain?
DNA.
What do all cells contain that perform most cell functions?
Proteins.
What is a prokaryotic cell characterized by?
Having DNA without a nucleus.
What distinguishes eukaryotic cells from prokaryotic cells?
Eukaryotic cells have a membrane-enclosed nucelus.
What is the composition of the cell membrane?
A phospholipid bilayer.
How does cholesterol affect membrane fluidity?
It increases fluidity at lower temperatures by pushing phospholipids apart.
What model describes the structure of the cell membrane?
The Fluid Mosaic Model.
What are peripheral membrane proteins primarily characterized by?
They are mostly hydrophilic and associate with one side of the membrane.
What is the function of integral membrane proteins?
They are amphipathic and span the membrane, facilitating transport and signaling.
What is selective permeability in cell membranes?
The ability of the membrane to regulate what can enter or exit the cell.
What is simple diffusion?
The movement of particles down a concentration gradient without energy.
What is facilitated transport?
The movement of particles through membrane proteins, requiring no energy.
What is active transport?
The movement of particles against their concentration gradient, requiring energy.
What is the Na(sodium)/K(potassium) pump an example of?
Active transport that creates an electrochemical gradient.
What are the two types of bulk transport?
Exocytosis (out of the cell) and endocytosis (into the cell).
What limits the size of cells?
The surface-to-volume ratio; as size increases, volume increases faster than surface area.
What is the main purpose of compartmentalization in eukaryotic cells?
To seperate different cellular processes and enhance efficiency.
What are the main components of a eukaryotic cell?
Nucelus, nucleolus, nuclear envelope, ribosomes, endomembrane system (including ER, Golgi apparatus, lysosomes, vacuoles, vesicles), mitochondria, chloroplasts, cytoskeleton, and cell wall.
What is the function of the nucelus in a eukaryotic cell?
It stores genetic information (DNA) as chromosomes and is surrounded by a nuclear envelope that has nuclear pores for trafficking.
What is chromatin?
Chromatin is the structure formed when chromosomes warp around proteins and extend throughout the nucleus.
What is the endomembrane system?
A network of membranes that connects multiple organelles, including the nucleus, to prepare and transport proteins and lipids.
What are the two types of endoplasmic reticulum (ER) and their functions?
Rough ER, which has ribosomes and specializes in protein production, and Smooth ER, which focuses on lipid synthesis.
What is the role of ribosomes in a cell?
Ribosomes are ribonucleoprotein complexes that synthesize proteins using messenger RNA as a template.
What does the Golgi apparatus do?
It sorts, modifies (such as glycoprotein formation), and sends proteins and lipids to their target locations.
What is the function of lysosomes?
Lysosomes contain digestive enzymes that degrade various biomolecules and have a pH of approximately 5.
What are veiscles and vacuoles?
Vesicles are small membrane-bound structures that transport molecules, while vacuoles are larger vesicles that store substances within the cell.
What is the primary function of mitochondria?
Mitochondria are responsible for respiration and ATP production from gluocse in almost all eukaryotes.
What is the role of chloroplasts?
Chloroplasts are responsible for photosynthesis, converting CO2 and water into gluoce and oxygen.
What is the endosymbiosis theory?
The theory suggets that mitochondria and chloroplasts originated from prokaryotic cells that entered into a symbiotic relationship with ancestral eukaryotic cells.
What is the cyoskeleton and its components?
The cytoskeleton provides structural support and movement within the cell, composed of microtubules, microfilaments, and intermediate filaments.
What are microtubules and their functions?
Microtubules are large, hollow tubes that provide structure, are important for cell division, and serve as tracks for vesicle movement.
What are motor proteins and their roles?
Motor proteins are like myosin, kinesin, and dynein transport vesicles or organelles along microtubules and microfilaments using ATP.
What are microfilaments and their functions?
Microfilaments are the thinnest cytoskeletal elements involved in vesicular transport and muscle contraction.
What are intermediate filaments?
Intermediate filaments are sturdy, cable-like structures found only in animal cells that help maintain cell structure and link multiple cells.
What is the significance of the nuclear envelope?
The nuclear envelope is a double-bilayer membrane that separates the nucelus from the cytoplasm and is connected to the endomembrane system.
What is the function of the nucleolus?
The nucleolus is an area within the nucleus responsible for the production of ribosomal RNA (rRNA).
What is the role of the cell wall in eukaryotic cells?
The cell wall provides structural support and protection, primarily found in plant cells and fungi.
How does exocytosis occur in the endomembrane system?
Exocytosis involves the fusion of vesicles with the cell membrane, releasing their contents outside the cell.
What is the relationship between mitochondria and chloroplasts?
Both organelles contain ribosomes, circular DNA, and are involved in energy production, with mitochondria focusing on respiration and chloroplasts on photosynthesis.
What is the importance of selective permeability in cell membranes?
Slective permeability allows cells to regulate the entry and exit of substances, maintaining homeostasis.
What is the function of vacuoles?
Vacuoles store substances such as nutrients, waste products, or water within the cell.
What is the significance of the pH in lysosomes?
The acidic pH (~5) in lysosomes is crucial for the optimal activity of digestive enxymes that break down biomolecules.