anaphy chapter 3 Flashcards
What is the cell theory, and why is it fundamental to understanding biology?
The cell theory states that all living organisms are composed of one or more cells, the cell is the basic unit of life, and all cells arise from pre-existing cells. This theory is fundamental because it establishes that the cell is the basic structural and functional unit of all living organisms.
What distinguishes eukaryotic cells from prokaryotic cells?
Eukaryotic cells have a true nucleus enclosed by a membrane and contain membrane-bound organelles, whereas prokaryotic cells lack a nucleus and membrane-bound organelles.
Describe the fluid mosaic model of the plasma membrane.
The fluid mosaic model describes the plasma membrane as a dynamic structure where lipids and proteins can move laterally within the layer. The membrane is composed of a bilayer of phospholipids with embedded proteins, which allows the membrane to be flexible while maintaining its structural integrity.
What roles do phospholipids, proteins, and carbohydrates play in the plasma membrane?
Phospholipids form the basic structure of the membrane, creating a hydrophobic barrier. Proteins serve various functions, including transport, signal reception, and structural support. Carbohydrates, often attached to proteins or lipids, are involved in cell recognition and communication.
Explain the difference between passive and active transport.
Passive transport does not require energy and occurs when molecules move from an area of higher concentration to one of lower concentration (e.g., diffusion, osmosis). Active transport requires energy, typically in the form of ATP, to move molecules against their concentration gradient (e.g., sodium-potassium pump).
What is osmosis, and how does it affect cells in hypotonic, hypertonic, and isotonic environments?
Osmosis is the diffusion of water across a semipermeable membrane. In a hypotonic environment, water enters the cell, causing it to swell. In a hypertonic environment, water leaves the cell, causing it to shrink. In an isotonic environment, there is no net water movement, and the cell remains the same size.
Describe the sodium-potassium pump and its significance.
The sodium-potassium pump is an active transport mechanism that moves three sodium ions out of the cell and two potassium ions into the cell against their concentration gradients. This pump is crucial for maintaining the cell’s electrochemical gradient, which is essential for processes like nerve impulse transmission.
What is the cytoplasm, and what are its primary components?
The cytoplasm is the material within a cell, excluding the nucleus. It consists of cytosol, a gel-like substance, and the organelles, which perform specific functions necessary for cellular life.
Compare the rough and smooth endoplasmic reticulum in terms of structure and function.
The rough endoplasmic reticulum (RER) is studded with ribosomes and is involved in protein synthesis and processing. The smooth endoplasmic reticulum (SER) lacks ribosomes and is involved in lipid synthesis, detoxification, and calcium storage.
What is the function of lysosomes in a cell?
Lysosomes contain digestive enzymes that break down waste materials, cellular debris, and foreign invaders like bacteria, playing a key role in cellular waste disposal and recycling.
What is the primary function of mitochondria in cells?
Mitochondria are the powerhouse of the cell, responsible for producing ATP through cellular respiration, which provides energy for cellular processes.
Describe the structure of a mitochondrion.
Mitochondria have a double membrane structure, with an outer membrane and a highly folded inner membrane (cristae) that increases surface area for ATP production. The inner space, called the matrix, contains enzymes, DNA, and ribosomes.
How does the electron transport chain contribute to ATP production?
The electron transport chain, located in the inner mitochondrial membrane, uses high-energy electrons from NADH and FADH2 to pump protons across the membrane, creating a gradient. The flow of protons back through ATP synthase drives the production of ATP.
What are the main functions of the nucleus in a eukaryotic cell?
The nucleus houses the cell’s genetic material (DNA) and is responsible for regulating gene expression, storing hereditary information, and coordinating cell activities like growth, metabolism, and reproduction.
How is DNA organized within the nucleus?
DNA is organized into chromatin, which is composed of DNA wrapped around histone proteins. During cell division, chromatin condenses to form chromosomes.
What is the difference between transcription and translation?
Transcription is the process of copying a gene’s DNA sequence into messenger RNA (mRNA), which occurs in the nucleus. Translation is the process where the mRNA is decoded by ribosomes to synthesize proteins, occurring in the cytoplasm.
What are the main stages of the cell cycle?
The cell cycle consists of interphase (G1, S, and G2 phases) where the cell grows and DNA is replicated, and the mitotic phase (mitosis and cytokinesis) where the cell divides.
How does mitosis differ from meiosis?
Mitosis is a process of cell division that results in two genetically identical daughter cells, used for growth and repair. Meiosis is a special type of cell division that produces four genetically unique gametes, used for sexual reproduction.
What is the role of checkpoints in the cell cycle?
Checkpoints in the cell cycle ensure that each stage is completed accurately, preventing errors such as DNA damage from being passed on to daughter cells. They can halt the cycle to allow for repairs or trigger apoptosis if the damage is irreparable.
What roles do mRNA, tRNA, and rRNA play in protein synthesis?
mRNA carries the genetic code from DNA to the ribosome, tRNA brings the correct amino acids to the ribosome, and rRNA forms the core of the ribosome’s structure and catalyzes peptide bond formation.
Describe the process of translation.
During translation, the ribosome reads the mRNA codons, and tRNA molecules bring the corresponding amino acids, which are linked together to form a polypeptide chain, eventually folding into a functional protein.
What are the different types of cell signaling mechanisms?
Autocrine signaling occurs when a cell targets itself, paracrine signaling targets nearby cells, and endocrine signaling involves hormones that travel through the bloodstream to distant cells.
How do receptor proteins facilitate cellular communication?
Receptor proteins on the cell surface or inside the cell bind to signaling molecules (ligands) and trigger a response in the cell, such as activating a signaling pathway or gene expression.
What is apoptosis, and why is it important?
Apoptosis is programmed cell death, a process that eliminates damaged or unnecessary cells without causing harm to the surrounding tissue, crucial for development and maintaining cellular health.
