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.
How does cellular aging affect cell function?
Cellular aging leads to a decline in cellular function, reduced ability to divide, and increased susceptibility to damage. This process contributes to the aging of tissues and organisms.
What is the Hayflick limit, and how does it relate to aging?
The Hayflick limit refers to the number of times a normal human cell can divide before it stops due to telomere shortening. This limit is associated with the aging process as cells lose the ability to proliferate.
Which of the following statements is NOT part of the cell theory?
A) All living organisms are composed of one or more cells.
B) The cell is the most basic unit of life.
C) All cells have a nucleus.
D) All cells arise from pre-existing cells
C) All cells have a nucleus.
Which of the following is true about prokaryotic cells?
A) They have a well-defined nucleus.
B) They lack membrane-bound organelles.
C) They are generally larger than eukaryotic cells.
D) They have a complex cytoskeleton.
B) They lack membrane-bound organelles
The plasma membrane’s primary function is to:
A) Generate energy for the cell.
B) Control what enters and exits the cell.
C) Store genetic information.
D) Produce proteins.
B) Control what enters and exits the cell.
Which component of the plasma membrane is primarily responsible for its fluid nature?
A) Carbohydrates
B) Cholesterol
C) Integral proteins
D) Phospholipids
D) Phospholipids
The fluid mosaic model describes the plasma membrane as:
A) A rigid, static structure.
B) A double layer of protein molecules.
C) A flexible layer made of phospholipids with proteins embedded within it.
D) A single layer of carbohydrates and proteins.
C) A flexible layer made of phospholipids with proteins embedded within it
Which of the following is a function of membrane proteins?
A) Act as enzymes to speed up chemical reactions.
B) Serve as recognition sites for cell-cell communication.
C) Transport molecules across the membrane.
D) All of the above.
D) All of the above.
Passive transport differs from active transport because:
A) Passive transport requires energy, while active transport does not.
B) Active transport moves substances down their concentration gradient.
C) Passive transport moves substances down their concentration gradient without energy.
D) Active transport involves osmosis, while passive transport involves diffusion.
C) Passive transport moves substances down their concentration gradient without energy.
In osmosis, water moves:
A) From a hypertonic solution to a hypotonic solution.
B) From a hypotonic solution to a hypertonic solution.
C) Equally in both directions across the membrane.
D) Against the concentration gradient.
B) From a hypotonic solution to a hypertonic solution
The sodium-potassium pump:
A) Moves sodium ions into the cell and potassium ions out of the cell.
B) Requires ATP to function.
C) Is an example of facilitated diffusion.
D) Moves sodium and potassium ions in equal numbers.
B) Requires ATP to function.
The rough endoplasmic reticulum (RER) is associated with:
A) Lipid synthesis.
B) Protein synthesis.
C) Carbohydrate metabolism.
D) Energy production.
B) Protein synthesis
the cytoplasm is composed of:
A) Cytosol, organelles, and inclusions.
B) DNA and RNA.
C) Proteins and lipids only.
D) Just organelles.
A) Cytosol, organelles, and inclusions.
Which organelle contains digestive enzymes that break down waste materials and cellular debris?
A) Lysosome
B) Mitochondrion
C) Ribosome
D) Golgi apparatus
A) Lysosome
The Golgi apparatus is responsible for:
A) Energy production.
B) Protein modification and sorting.
C) DNA replication.
D) Cellular respiration.
B) Protein modification and sorting.
The primary function of mitochondria is:
A) Protein synthesis.
B) ATP production.
C) Lipid storage.
D) Photosynthesis
B) ATP production.
Which of the following best describes the inner membrane of the mitochondrion?
A) It is smooth and featureless.
B) It contains cristae to increase surface area.
C) It is involved in protein synthesis.
D) It functions in DNA replication
B) It contains cristae to increase surface area
The electron transport chain, involved in ATP production, is located in the:
A) Cytosol
B) Inner mitochondrial membrane
C) Plasma membrane
D) Nucleus
B) Inner mitochondrial membrane
The nucleus of a cell contains:
A) Cytoplasm.
B) Genetic material (DNA).
C) Ribosomes.
D) Mitochondria
B) Genetic material (DNA)
Chromatin is:
A) A type of protein found in the cytoplasm.
B) DNA wrapped around histone proteins.
C) RNA that is being translated into protein.
D) The liquid portion of the cytoplasm
B) DNA wrapped around histone proteins.
Transcription is the process of:
A) Converting DNA into RNA.
B) Synthesizing proteins from amino acids.
C) Replicating DNA before cell division.
D) Modifying proteins in the Golgi apparatus.
A) Converting DNA into RNA.
During which phase of the cell cycle does DNA replication occur?
A) G1 phase
B) S phase
C) G2 phase
D) M phase
B) S phase
Which of the following best describes mitosis?
A) It reduces the chromosome number by half.
B) It results in two genetically identical daughter cells.
C) It occurs in germ cells only.
D) It includes the division of the cytoplasm.
B) It results in two genetically identical daughter cells
Cytokinesis in animal cells differs from plant cells in that:
A) Animal cells form a cell plate, while plant cells do not.
B) Animal cells divide the cytoplasm using a cleavage furrow.
C) Plant cells undergo binary fission instead of cytokinesis.
D) Animal cells do not use a spindle apparatus during division.
B) Animal cells divide the cytoplasm using a cleavage furrow.
A critical checkpoint that ensures DNA is undamaged and fully replicated occurs at the:
A) G1/S checkpoint
B) S/G2 checkpoint
C) G2/M checkpoint
D) Metaphase checkpoint
C) G2/M checkpoint
mRNA is responsible for:
A) Carrying genetic information from DNA to the ribosome.
B) Transferring amino acids to the ribosome during protein synthesis.
C) Forming the structure of the ribosome.
D) Modifying proteins after translation
A) Carrying genetic information from DNA to the ribosome.
Translation occurs in the:
A) Nucleus
B) Cytoplasm at the ribosome
C) Golgi apparatus
D) Mitochondria
B) Cytoplasm at the ribosome
A codon is a sequence of three nucleotides that:
A) Signals the start of DNA replication.
B) Specifies a particular amino acid during protein synthesis.
C) Marks the end of a gene.
D) Is involved in the folding of proteins.
B) Specifies a particular
Which of the following structures is found inside the nucleus?
A) Mitochondria
B) Ribosomes
C) Chromatin
D) Golgi apparatus
C) Chromatin
The nuclear envelope is composed of how many membranes?
A) One
B) Two
C) Three
D) Four
Answer: B) Two
The nucleolus is primarily involved in the production of:
A) DNA
B) Ribosomal RNA (rRNA)
C) mRNA
D) tRNA
Answer: B) Ribosomal RNA (rRNA)
Which of the following is NOT a function of the nucleus?
A) Storing genetic information
B) Regulating gene expression
C) Synthesizing proteins
D) Directing cell division
Answer: C) Synthesizing proteins
What is the function of nuclear pores?
A) To store DNA
B) To regulate the passage of molecules between the nucleus and cytoplasm
C) To synthesize ribosomes
D) To protect the DNA
B) To regulate the passage of molecules between the nucleus and cytoplasm
The nuclear matrix is:
A) A network of fibers within the nucleus providing structural support
B) A layer of enzymes that repairs DNA
C) The site of ribosome assembly
D) The liquid component of the nucleus
A) A network of fibers within the nucleus providing structural support
Which of the following describes euchromatin?
A) Tightly packed DNA, transcriptionally inactive
B) Loosely packed DNA, transcriptionally active
C) DNA that is found only in the nucleolus
D) DNA that has been permanently silenced
B) Loosely packed DNA, transcriptionally active
What is the role of histones in the nucleus?
A) They replicate DNA
B) They help package DNA into chromatin
C) They produce RNA
D) They are involved in protein synthesis
B) They help package DNA into chromatin
