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Lecture 1What makes up a plant?- Multicellular, cellulose-rich cell wall, chlorophyll and photosynthetic, life on landPlant structure- Shoot: grows above, includes stem, leaves, nodes, internodes, buds- Root: grows below ground, anchors, absorbs water/mineralsShoot- Flowers: where reproduction occurs, fruits & seeds develop- Leaves: site of photosynthesis, blade, petiole- Node: Place in the stem where a leaf is attached- Stem: holds leaves, transports water and nutrients, provides support above groundRoot- Anchor the plant to the soil- Absorb water and mineral nutrients- May serve as storage in some species (radish, yam)- Branch roots, root hairs, root cap*Potato is a stem that grows underground*Celery is an overgrown leaf petioleIndeterminate growth- Growth that is not terminated, not like animalsShoot and Root apical meristems- Region of embryonic tissue capable of developing new parts of the plantLecture 2The Molecules of Life- Carbohydrates (sugars, starches, cellulose)- Lipids (fats, oils, waxes, phospholipids, steroids)- Proteins (amino acids)- Nucleic Acids (DNA, RNA)4 Characteristics of Life’s molecules- Carbon-based- Formed from a few elements: C, H, O, P, N- Made from simple building blocks (carbs=sugars, lipids=fatty acids, proteins=amino acids, and nucleic acids=nucleotides)- Function depends on structure Charbohydrates- Organic molecules composed of C, H, O (1:2:1 ratio)- Most abundant of life’s molecules- 3 types of carbs: monosaccharaides (simple sugar of 3 to 6 carbon like glucose, fructose, and ribose), disaccharides (two mono, like sucrose, maltose, and lactose), polysaccharides (many long chains of mono like starch, and cellulose which is in plant cells walls)- its function is energy storage, structure (cellulose), and carbon sources to make molecules like amino acids Lipids- Usually composed of C, O, H atoms (sometimes P)- 3 types: fats oils and waxes, phospholipids, and steroids- Fats and lipids are water insoluble and made from two building blocks: glycerol molecule and fatty acids (if the molecule is stacked and solid it is fat, if broken or bent it is liquid, so molecular structure determines solid or liquid) fatty acid chains are hydrophobic (water hating)- They are solid at room temp, usually animal-derived, oils are liquid lipids- Phospholipids contain phosphorus (a phosphate group), which make the head hydrophilic (water loving), the membranes of cells is a lipid bilayer- Steroids are composed of 4 carbon rings and side groups, include sex hormones, cortisol, cholesterol, and others- Function of lipids is to be a high-energy food, part of cell membrane, used as hormones, waxes, vitamins, and pigments- Energy storage works as: monoglycerides (glycerol + 1 fatty acid chain), diglycerides (monoglyercide + 2nd fatty acid chain), and triglyceride (dicglyceride + 3rd fatty acid chain), triglyceride is the highest energyProteins - Large complex molecules, composed of CHOSN, building blocks are amino acids- Function is the building blocks of cells, transport what passes through plasma membrane, in animal structure is our hair, nails, muscles, etc, and used as enzymes so they speed up chemical reactionsNucleic Acids- Large organic molecules, composed of CHOPN, basic unit is the nucleotide: sugar, phosphate, and nitrogenous base- Nucleic acids are long chains of nucleotides, an example is DNA and RNA, andATP (energy transfer exchange)- Function is information storage, and energy carrierCell- Basic building blocks of living organisms, form tissues and organs, each is functionally independent and can live on its own in the right conditions- All plants are composed of cells- Was discovered by Hooke in 1665- Cell theory: cell is basic unit of life, organisms are composed of cells, cells arise from other cells- Two types: prokaryotic (lack organelles, are simple, like bacteria), and eukaryotic (have organelles like cells of plants and animals)The Plant Cell- Plant cells have 4 things that animal cells don’t: cell walls, chloroplasts, plasmodesmata, and vacuoles and they can potentially create a whole plant from a single cell (plant cloning) because they function independently- The outside is the cell wall then plasma membrane- Cell wall protects and supports, made mostly of cellulose, allows water and other molecules to pass through- Primary cell wall is formed early, located on the outermost layer, it is mostly cellulose, secondary is deposited on the inside, between primary and plasmamembrane, and the middle lamella is what glues cells together made mostly of carbs- Plasmodesmata is the cytoplasmic connection between adjacent cells, allows for the movement of materials form cell to cell- Plasma membrane is a lipid bilayer, hydrophilic heads are outer and hydrophobic tails are inside, is differentially permeable, lets water pass through but not other molecules- In the fluid mosaic model, it is a double layer of phospholipids with scattered proteins- Cytosol is 90% water, proteins, organic molecules, and ions- Cytoplasm is cytosol and organelles only (except nucleus)- Protoplast is all of the plant cell enclosed by the cell wall - Microtubules and microfilaments make up the cytoskeleton, a network of protein “cables” that provide structural support and they help in cell division and elongation, is important for mitosis- Nucleus contains all genetic information, chromosomes are DNA and proteins, nucleolus are bodies where ribosomes are made, ribosomes are sitefor protein synthesis and use DNA to produce proteins it is not membrane bound- Mitochondria provide energy to cell by converting sugars into chemical energy (powerhouse)- Chloroplasts are the site for photosynthesis contain chlorophyll- Vacuole stores a watery solution of sugars, salts, acids, and proteins, makes us 90% of cell volume, makes cell turgid, has its own membrane (tonoplast)- Endoplasmic reticulum is a network of folded membranes throughout the cytoplasm, smooth ER lacks ribosomes, used for packaging and transport of proteins, also to make lipids rough ER has ribosomes - Golgi apparatus: stack of flattened hollow membranous sacks, modifies proteins, lipids from the ER, packages in vesicles (UPS of the cell)- Endosymbiont theory: chloroplasts and mitochondria are descendants of prokaryotes that were engulfed by larger cells, establishing a symbiotic

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UMD BSCI 124 - Lecture notes

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