Cell Structure, Membrane, Transport, DNA, Cell Cycle and Mitosis

Flashcards covering cell structure, plasma membrane, transport mechanisms, DNA, the cell cycle, mitosis, and cell aging based on the lecture notes.

What is cytology?

The study of cells.

What is the typical measurement unit for cells, and how do their sizes and shapes vary?

Cells are measured in micrometers (µm). Sizes vary from 7µm (RBC) to 120µm (oocyte), and shapes vary (flat, cylindrical, oval, irregular) depending on location and function.

What are the three main types of microscopy used to study cells?

Light microscopy (LM), Transmission electron microscopy (TEM), and Scanning electron microscopy (SEM).

How do Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) differ?

TEM produces a 2D image by passing electrons through a thin specimen, while SEM provides a 3D image of the cell surface by bouncing electrons off it.

Name some general cellular/tissue functions.

Covering, Lining, Storage, Movement, Connection, Defense, Communication, and Reproduction.

What are the three basic parts nearly all human cells have?

Plasma membrane, Cytoplasm, and Nucleus.

What is the primary function of the plasma membrane?

It serves as a selective permeable barrier that regulates the passage of gases, nutrients, and wastes between the internal and external environments of the cell.

What are the major components of the plasma membrane?

Lipids (phospholipids, cholesterol, glycolipids, lipoproteins) and proteins (integral and peripheral).

What are the main functions of the plasma membrane?

Communication, intercellular connection, physical barrier, and selective permeability.

Describe the structure of a phospholipid and how phospholipids form the bilayer in the plasma membrane.

Each phospholipid has a polar (charged) head region and a nonpolar (uncharged) tail region. They form a bilayer where polar heads face the aqueous environments (outside and inside the cell), and nonpolar tails face each other, forming the membrane's internal core.

What is the role of cholesterol in the plasma membrane?

Cholesterol stabilizes the two layers of the phospholipid bilayer, strengthening and stabilizing the membrane against extreme temperatures.

What is the glycocalyx and what is its function?

The glycocalyx is formed by carbohydrate molecules attached to glycolipids and glycoproteins on the outer surface of the plasma membrane, aiding in cell-to-cell attachment and signaling cell type.

Differentiate between integral and peripheral proteins in the plasma membrane.

Integral proteins are embedded in and often span the entire thickness of the phospholipid bilayer, while peripheral proteins are loosely attached to the external or internal surface of integral proteins.

What are some functions of proteins embedded within or associated with the plasma membrane?

Transport, intercellular connection, anchorage for the cytoskeleton, enzyme (catalytic) activity, cell-cell recognition, and signal transduction.

What factors influence membrane permeability for transport across the plasma membrane?

Type of transport proteins, plasma membrane structure, concentration gradient, ionic charge, lipid solubility, and molecular size.

What is the difference between passive transport and active transport?

Passive transport moves substances down their concentration gradient without requiring cellular energy (ATP), while active transport moves substances against their concentration gradient and requires ATP.

What are the two general types of passive transport involving diffusion?

Osmosis (movement of water) and Dialysis (movement of solutes), which includes simple diffusion, facilitated diffusion, and bulk filtration.

What is osmosis?

The diffusion of water, where water moves from a region of higher concentration to a region of lower concentration across a membrane (driven by osmotic pressure).

Describe simple diffusion.

The movement of small and/or nonpolar molecules down their concentration gradient directly through the phospholipid bilayer, such as O2 and CO2.

What is facilitated diffusion?

The movement of large and/or polar molecules across a membrane, assisted by specific transport proteins (carrier molecules), down their concentration gradient.

Describe active transport and provide an example.

Active transport moves substances across a membrane against their concentration gradient, requiring energy in the form of ATP. An example is the sodium-potassium pump, which moves Na+ and K+ in opposite directions against their gradients.

What is bulk transport, and what are its two main types?

Bulk transport is a type of active transport that moves large molecules or bulk structures across the plasma membrane. Its two types are exocytosis (out of the cell) and endocytosis (into the cell).

Describe the process of exocytosis.

Materials packaged into vesicles are secreted out of the cell. Vesicles fuse with the plasma membrane, releasing their contents (e.g., proteins) extracellularly, and the vesicle membrane becomes part of the cell membrane.

What are the three forms of endocytosis?

Phagocytosis ('cell eating'), Pinocytosis ('cell drinking'), and Receptor-mediated endocytosis.

How does phagocytosis differ from pinocytosis?

Phagocytosis is the nonspecific uptake of particles by forming membrane extensions (pseudopodia) that engulf the particles, while pinocytosis is the nonspecific uptake of extracellular fluid.

What is receptor-mediated endocytosis?

The engulfing of specific molecules that are bound to receptors on the surface of the plasma membrane, often a two-step process.

What are the three main components of the cytoplasm?

Cytosol, Inclusions, and Organelles.

What is the cytosol composed of?

A viscous, jelly-like fluid containing dissolved substances such as ions, nutrients, proteins, carbohydrates, lipids, and other small molecules.

What are inclusions, and provide examples.

Inclusions are large storage aggregates of complex molecules found in the cytosol. Examples include melanin (black pigment), glycogen (sugar chains), and carotene (yellow/orange pigment).

What are organelles, and how are they classified?

Organelles are 'little organs' within a cell that perform different functions. They are classified as either membrane-bound or non-membrane-bound.

List some examples of membrane-bound organelles.

Endoplasmic Reticulum (ER), Golgi apparatus, Lysosomes, Peroxisomes, and Mitochondria.

What is the endoplasmic reticulum (ER), and what are its two types?

The ER is a series of tubes and channels for transport of proteins and other substances. Its two types are the Smooth Endoplasmic Reticulum (SER) and the Rough Endoplasmic Reticulum (RER).

What are the main functions of the Smooth Endoplasmic Reticulum (SER)?

Synthesis, transport, and storage of lipids (including steroid hormones), metabolism of carbohydrates, and detoxification of drugs, alcohol, and poisons.

What distinguishes the Rough Endoplasmic Reticulum (RER), and what is its primary function?

The RER has ribosomes attached to its outer surface, giving it a 'rough' appearance. Its primary function is to synthesize and transport proteins destined for secretion, incorporation into the plasma membrane, or as enzymes within lysosomes.

What is the function of the Golgi apparatus?

It receives proteins and lipids from the RER for modification, packaging, and secretion into vesicles, also sorting materials for lysosomes and plasma membrane incorporation.

Describe the general flow of proteins through the Golgi apparatus.

Proteins synthesized in the RER are packaged into transport vesicles, which then fuse with the receiving (cis-face) region of the Golgi apparatus. The proteins are modified as they move through the Golgi, packaged into secretory vesicles from the shipping (trans-face) region, and then either participate in exocytosis or become lysosomes.

What are lysosomes, and what is their function?

Lysosomes are vesicles generated by the Golgi apparatus that contain enzymes for intracellular digestion, breaking down waste products and damaged organelles (autophagy). They can also cause autolysis (digestion of the entire cell) when a cell is dying.

What are peroxisomes and what do they do?

Peroxisomes are vesicles formed from the rough ER that are similar to but smaller than lysosomes. They use O2 and the enzyme catalase to detoxify toxins and poisons taken into the cell.

Describe the structure and function of mitochondria.

Mitochondria are double-membrane bound organelles with an inner membrane folded into cristae. Their main function is to produce ATP through cellular respiration, earning them the name 'powerhouses' of the cell.

List some examples of non-membrane-bound organelles.

Ribosomes, Cytoskeleton (microfilaments, intermediate filaments, microtubules), Centrosomes and centrioles, Cilia and flagella, and Microvilli.

What are ribosomes responsible for, and where can they be found?

Ribosomes are responsible for protein synthesis. They can be found as free ribosomes unattached in the cytosol or as fixed ribosomes attached to the outer surface of the Rough ER.

What are the three components of the cytoskeleton?

Microfilaments, Intermediate filaments, and Microtubules.

What are microfilaments composed of and what are their functions?

They are composed of actin proteins intertwined in helical strands, along with myosin. They maintain and change cell shape, and participate in muscle contraction and some cell division.

What is the function of intermediate filaments?

They provide structural support and stabilize junctions between opposed cells.

What are microtubules composed of and what are their functions?

They are composed of tubulin protein and radiate from the centrosome. Functions include fixing organelles in place, maintaining cell shape and rigidity, enabling cyclosis (cytoplasmic streaming), cell motility (in cilia and flagella), and moving chromosomes during cell division.

Describe the centrosome and centrioles, and their roles.

The centrosome is a nonmembranous, spherical structure adjacent to the nucleus, containing a pair of centrioles at right angles. Centrioles are composed of nine sets of microtubule triplets and are involved in organizing microtubules and attaching to chromosomes during cell division for chromosomal migration.

How do cilia and flagella differ in structure and function?

Cilia are grouped projections containing microtubules that move objects across the cell surface (e.g., respiratory tree, oviduct). Flagella are longer, usually singular projections used to propel the cell itself (e.g., sperm).

What are microvilli and what is their purpose?

Microvilli are thin, microscopic projections extending from the plasma membrane that are not capable of motion. Their purpose is to slow the movement of digested substances to aid in absorption, such as on the surface of small intestine cells.

What is the primary role of the nucleus, and what are its three major components?

The nucleus is the control center for cellular activity. Its three major components are the nuclear envelope, nucleoli, and DNA (chromatin and chromosomes).

What is the nuclear envelope?

It is a double membrane structure that controls the entry and exit of molecules from the nucleus and cytoplasm via nuclear pores. Its outer membrane is continuous with the endoplasmic reticulum.

What are nucleoli and what is their function?

Nucleoli are composed of RNA, enzymes, and various proteins, and are responsible for making the components of ribosomes.

Explain the relationship between DNA, chromatin, chromosomes, and genes.

The nucleus houses deoxyribonucleic acid (DNA), our genetic material. When the cell is not dividing, DNA is unwound into fine filaments called chromatin. During cell division, chromatin coils tightly to form chromosomes. A gene is a segment of genetic material (nucleotides) that makes a specific trait.

What are the two main states in the life cycle of a cell?

Interphase (maintenance/resting phase) and Mitotic phase (when the cell divides).

What are the three stages of interphase and their key activities?

G1 Phase (normal cell growth, organelle replication, protein production for replication, and centriole formation). S Phase ('Synthesis' phase where DNA replicates). G2 Phase (centriole replication completion, continued organelle production, and synthesis of enzymes for cell division).

What two distinct events occur during the mitotic phase?

Mitosis (division of the nucleus) and Cytokinesis (division of the cytoplasm, which occurs during telophase).

What are the four consecutive stages of mitosis?

Prophase, Metaphase, Anaphase, and Telophase.

Describe the key events of Prophase.

Chromatin supercoils forming chromosomes (duplicate, identical sister chromatids joined at a centromere). Spindle fibers begin to grow from centrioles. The nuclear envelope breaks up at the end of prophase.

Describe the key events of Metaphase.

Chromosomes line up along the equatorial plate, and spindle fibers attach to the centromere of sister chromatids, forming the mitotic spindle.

Describe the key events of Anaphase.

Spindle fibers pull sister chromatids apart to opposite ends of the dividing cell by breaking the centromere.

Describe the key events of Telophase.

The nuclear envelope re-forms around each set of chromosomes, chromosomes begin to uncoil, and spindle fibers disappear. A cleavage furrow appears, leading to complete cytoplasmic division (cytokinesis).

What are the two general ways cells can die?

Necrosis (abnormal/accelerated cell death) and Apoptosis (programmed cell death).

What is cytology?

The study of cells.

What is the typical measurement unit for cells, and how do their sizes and shapes vary?

Cells are measured in micrometers (µm). Sizes vary from 7µm (RBC) to 120µm (oocyte), and shapes vary (flat, cylindrical, oval, irregular) depending on location and function.

What are the three main types of microscopy used to study cells?

Light microscopy (LM), Transmission electron microscopy (TEM), and Scanning electron microscopy (SEM).

How do Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) differ?

TEM produces a 2D image by passing electrons through a thin specimen, while SEM provides a 3D image of the cell surface by bouncing electrons off it.

Name some general cellular/tissue functions.

Covering, Lining, Storage, Movement, Connection, Defense, Communication, and Reproduction.

What are the three basic parts nearly all human cells have?

Plasma membrane, Cytoplasm, and Nucleus.

What is the primary function of the plasma membrane?

It serves as a selective permeable barrier that regulates the passage of gases, nutrients, and wastes between the internal and external environments of the cell.

What are the major components of the plasma membrane?

Lipids (phospholipids, cholesterol, glycolipids, lipoproteins) and proteins (integral and peripheral).

What are the main functions of the plasma membrane?

Communication, intercellular connection, physical barrier, and selective permeability.

Describe the structure of a phospholipid and how phospholipids form the bilayer in the plasma membrane.

Each phospholipid has a polar (charged) head region and a nonpolar (uncharged) tail region. They form a bilayer where polar heads face the aqueous environments (outside and inside the cell), and nonpolar tails face each other, forming the membrane's internal core.

What is the role of cholesterol in the plasma membrane?

Cholesterol stabilizes the two layers of the phospholipid bilayer, strengthening and stabilizing the membrane against extreme temperatures.

What is the glycocalyx and what is its function?

Carbohydrate molecules (from glycolipids and glycoproteins) on the outer plasma membrane. Its functions are cell-to-cell attachment and signaling cell type.

Differentiate between integral and peripheral proteins in the plasma membrane.

Integral proteins are embedded in and often span the entire thickness of the phospholipid bilayer, while peripheral proteins are loosely attached to the external or internal surface of integral proteins.

What are some functions of proteins embedded within or associated with the plasma membrane?

Transport, intercellular connection, anchorage for the cytoskeleton, enzyme (catalytic) activity, cell-cell recognition, and signal transduction.

What factors influence membrane permeability for transport across the plasma membrane?

Type of transport proteins, plasma membrane structure, concentration gradient, ionic charge, lipid solubility, and molecular size.

What is the difference between passive transport and active transport?

Passive transport moves substances down their concentration gradient without requiring cellular energy (ATP), while active transport moves substances against their concentration gradient and requires ATP.

What are the two general types of passive transport involving diffusion?

Osmosis (movement of water) and Dialysis (movement of solutes), which includes simple diffusion, facilitated diffusion, and bulk filtration.

What is osmosis?

The diffusion of water, where water moves from a region of higher concentration to a region of lower concentration across a membrane (driven by osmotic pressure).

Describe simple diffusion.

The movement of small and/or nonpolar molecules down their concentration gradient directly through the phospholipid bilayer, such as O2 and CO2.

What is facilitated diffusion?

The movement of large and/or polar molecules across a membrane, assisted by specific transport proteins (carrier molecules), down their concentration gradient.

Describe active transport and provide an example.

Active transport moves substances across a membrane against their concentration gradient, requiring energy in the form of ATP. An example is the sodium-potassium pump, which moves Na+ and K+ in opposite directions against their gradients.

What is bulk transport, and what are its two main types?

Bulk transport is a type of active transport that moves large molecules or bulk structures across the plasma membrane. Its two types are exocytosis (out of the cell) and endocytosis (into the cell).

Describe the process of exocytosis.

Materials packaged into vesicles are secreted out of the cell. Vesicles fuse with the plasma membrane, releasing their contents (e.g., proteins) extracellularly, and the vesicle membrane becomes part of the cell membrane.

What are the three forms of endocytosis?

Phagocytosis ('cell eating'), Pinocytosis ('cell drinking'), and Receptor-mediated endocytosis.

How does phagocytosis differ from pinocytosis?

Phagocytosis is the nonspecific uptake of particles by forming membrane extensions (pseudopodia) that engulf the particles, while pinocytosis is the nonspecific uptake of extracellular fluid.

What is receptor-mediated endocytosis?

The engulfing of specific molecules that are bound to receptors on the surface of the plasma membrane, often a two-step process.

What are the three main components of the cytoplasm?

Cytosol, Inclusions, and Organelles.

What is the cytosol composed of?

A viscous, jelly-like fluid containing dissolved substances such as ions, nutrients, proteins, carbohydrates, lipids, and other small molecules.

What are inclusions, and provide examples.

Inclusions are large storage aggregates of complex molecules found in the cytosol. Examples include melanin (black pigment), glycogen (sugar chains), and carotene (yellow/orange pigment).

What are organelles, and how are they classified?

Organelles are 'little organs' within a cell that perform different functions. They are classified as either membrane-bound or non-membrane-bound.

List some examples of membrane-bound organelles.

Endoplasmic Reticulum (ER), Golgi apparatus, Lysosomes, Peroxisomes, and Mitochondria.

What is the endoplasmic reticulum (ER), and what are its two types?

The ER is a series of tubes and channels for transport of proteins and other substances. Its two types are the Smooth Endoplasmic Reticulum (SER) and the Rough Endoplasmic Reticulum (RER).

What are the main functions of the Smooth Endoplasmic Reticulum (SER)?

Synthesis, transport, and storage of lipids (including steroid hormones), metabolism of carbohydrates, and detoxification of drugs, alcohol, and poisons.

What distinguishes the Rough Endoplasmic Reticulum (RER), and what is its primary function?

The RER has ribosomes attached to its outer surface, giving it a 'rough' appearance. Its primary function is to synthesize and transport proteins destined for secretion, incorporation into the plasma membrane, or as enzymes within lysosomes.

What is the function of the Golgi apparatus?

It receives proteins and lipids from the RER for modification, packaging, and secretion into vesicles, also sorting materials for lysosomes and plasma membrane incorporation.

Describe the general flow of proteins through the Golgi apparatus.

Proteins synthesized in the RER are packaged into transport vesicles, which then fuse with the receiving (cis-face) region of the Golgi apparatus. The proteins are modified as they move through the Golgi, packaged into secretory vesicles from the shipping (trans-face) region, and then either participate in exocytosis or become lysosomes.

What are lysosomes, and what is their function?

Lysosomes are vesicles generated by the Golgi apparatus that contain enzymes for intracellular digestion, breaking down waste products and damaged organelles (autophagy). They can also cause autolysis (digestion of the entire cell) when a cell is dying.

What are peroxisomes and what do they do?

Peroxisomes are vesicles formed from the rough ER that are similar to but smaller than lysosomes. They use O2 and the enzyme catalase to detoxify toxins and poisons taken into the cell.

Describe the structure and function of mitochondria.

Mitochondria are double-membrane bound organelles with an inner membrane folded into cristae. Their main function is to produce ATP through cellular respiration, earning them the name 'powerhouses' of the cell.