Cell theory and structure (1) Flashcards
What are the 7 basic functions that all living things carry out? (HR MENG’S)
- Homeostasis: maintain a stable internal environment
- Reproduction: produce offspring, either sexually or asexually
- Metabolism: undertake essential chemical reactions
- Excretion: exhibit the removal of waste products
- Nutrition: exchange materials and gases with the environment
- Growth: move and change shape or size
- Sensitivity: respond to internal and external stimuli
What are the 3 exceptions to cell theory?
- Striated muscle: skeletal muscle is composed of muscle fibres that can measure 300mm or more and contain hundreds of nuclei.
- Aseptate fungi: fungi are made of thread-like structures called hyphae divided by septa, but in aseptate fungi these hyphae are not sectioned–they are uninterrupted tube-like structures with multiple nuclei.
- Giant algae: most algae consist of one microscopic cell, but giant algae can grow up to 100 mm in length while remaining unicellular with one nucleus.
(1 and 2 are not strictly composed of cells and 3 is much larger than cells should be)
Explain the cytoplasm, cytosol, and nucleoplasm.
Cytosol is the aqueous solution on the inside of a cell, in which a number of structures called cell organelles are suspended.
The cytoplasm is the cytosol and organelles located outside of the nucleus. Cytoplasmic streaming is a circular flow of cytoplasm within cells, which speeds distribution of materials
The nucleoplasm is the cytosol located inside the nucleus.
Describe what you know about what ribosomes are, their function, and their varying sizes.
Ribosomes are particles made of ribosomal RNA and protein that carry out protein synthesis:
- In the cytosol (free ribosomes) to produce proteins used in the cell
- On the outside of the endoplasmic reticulum or nuclear envelope (membrane-bound ribosomes) to produce proteins for secretion and use outside the cell
Prokaryotic cells have 70S ribosomes, and eukaryotic cells have 80S ribosomes.
What are the mitochondria?
Organelles where important chemical reactions occur in eukaryotic cells. They contribute to cell respiration, a series of chemical changes that produces compounds, a source of energy for cells. Many chemical reactions occur across folds in the inner membrane called cristae.
Describe whatever you know about the endoplasmic reticulum and its two types! (Try and hit what ER is, the distinct features and functions of the variations, and what comes after you’re done with the ER)
A system of membranes and proteins that connect with the nuclear envelope.
Rough endoplasmic reticulum is studded with ribosomes; smooth endoplasmic reticulum is not.
The RER’s bound ribosomes secrete glycoproteins (proteins covalently bonded to carbohydrates). The RER distributes transport vesicles, and is a membrane factory for the cell.
The SER synthesizes lipids, metabolizes carbohydrates, detoxifies poison, and stores calcium.
Products of the SER and RER become enclosed in transport vesicles and travel toward the Golgi apparatus.
Describe the cell membrane.
A membrane is composed of a bi-layer of lipid molecules called phospholipids and other compounds (proteins and carbohydrates). The parts of a membrane are fluid.
Describe the Golgi apparatus and its functions. (Ms. Min Sun)
The Golgi apparatus consists of flattened membranous sacs called cisternae. The cisternae have a cis (receiving) side and a trans (shipping) side
It:
- Modifies products of the ER
- Manufactures certain macromolecules
- Sorts / packages materials into transport vesicles
What are lysosomes and their function? Are they are found in plant or animal cells?
They are organelles that contain enzymes that break down cell-composing molecules into individual macromolecules. They may be used to digest food particles brought into the cell or destroy threatening microorganisms like bacteria and viruses.
They are found in animal cells.
What is the function of plastids and are they found in plant or animal cells?
They store materials that are useful to the cell and help keep it alive. They contain the chlorophyll necessary to perform photosynthesis. Chloroplasts (important plastids) contain chlorophyll, a pigment that enables the green colour of plants and the start of photosynthesis.
They are found in plant cells.
What are vacuoles and their function?
Vacuoles are usually large, membrane-bound sacs filled with a watery solution containing dissolved waste, food, and proteins. They are found in plant cells; the pressure inside one or two large vacuoles helps keep the cell membrane pressed firmly against the cell wall.
Explain the nucleus, its respective parts, and their functions.
The nucleus controls the cell’s activities. Inside it, DNA and proteins form genetic material called chromatin, which condenses to form discrete chromosomes.
The nuclear membrane is a porous double membrane that separates the nucleus from the cytoplasm.
The nucleoplasm is the cytosol inside the nucleus.
The nucleolus is the innermost part of the nucleus, and is the site of ribosomal RNA (rRNA) synthesis.
The nuclear lamina, composed of protein, maintains the shape of the nucleus.
What is the function of the endomembrane system and what are its components?
It regulates protein traffic and performs metabolic functions within the cell.
Components include:
- Nuclear envelope
- Endoplasmic reticulum
- Golgi apparatus
- Lysosomes
- Vacuoles
- Plasma membrane
All components are continuous or connected via vesicles.
Define endocytosis and its three variations: receptor mediated endocytosis, phagocytosis, and pinocytosis.
Endocytosis: process by which large substances (or smaller substances in bulk) enter the cell without crossing the membrane
There are three types of endocytosis:
Phagocytosis: process by which solids are ingested (usually to be transported to the lysosome)
Pinocytosis: process by which liquids / dissolved substances are ingested (allows faster entry than via protein channels)
Receptor-mediated: receptor proteins on the cell surface are used to capture a specific target molecule.
What are peroxisomes? (At last a short answer question, rejoice!)
They are oxidative organelles.
