Cell & Plant Biology Lecture Notes

Comprehensive vocabulary flashcards covering cellular biology, plant anatomy, physiological processes (photosynthesis and respiration), and growth regulators as presented in the Cedara College notes.

Prokaryotes

Unicellular organisms with cells that lack a nucleus and other organelles, with genetic material concentrated in a region called the nucleoid.

Eukaryotes

Organisms with cells that have genetic material enclosed within a nucleus and contain organelles such as mitochondria, chloroplasts, and Golgi bodies.

Cell wall

A structure composed of lignin and cellulose that provides external rigidity and support to plant cells.

Nucleolus

A round granular structure within the nucleus where ribosomal RNA is produced.

Ribosome

Granular organelles circulating freely in the cytoplasm or situated on the Endoplasmic Reticulum (ER) involved in protein synthesis.

Amyloplast

An organelle in some plant cells, such as tubers and fruits, that stores starch.

Rough endoplasmic reticulum (ER)

A membrane system that holds/supports ribosomes and assists in the packaging of proteins.

Golgi body / apparatus

Stacks of membranes used in transporting and packaging cellular substances.

Plasma membrane

A semi-permeable phospholipid membrane that controls the movement of substances into and out of the cell.

Smooth endoplasmic reticulum (ER)

A folded membrane system containing enzymes that function in lipid synthesis.

Mitochondrion

The site of cellular respiration where energy is released for cell activities.

Chloroplasts

Organelles containing pigments used for photosynthesis in plant cells.

Lysosome

Organelle containing proteins and enzymes that engulf and destroy waste products and harmful particles.

Vacuole

A fluid-filled organelle used for water storage and waste removal; large in plant cells and smaller/fewer in animal cells.

Metabolism

The sum total of chemical changes in living organisms resulting in growth, energy production, and waste elimination, including catabolic and anabolic reactions.

Catabolism

Destructive metabolism involving the conversion or breaking down of complex substances into simpler materials, such as the breakdown of glucose during respiration.

Anabolism

Constructive metabolism involving the conversion of simple substances into more complex substances, such as protein synthesis or photosynthesis.

Photosynthesis

The process through which light energy, $H_{2}O$, and $CO_{2}$ are converted to carbohydrate and $O_{2}$ in the presence of chlorophyll.

Thylakoid disks

Disk-shaped membrane structures in chloroplasts that contain chlorophyll and are the site of $ATP$ production.

Granum

A stack of thylakoid disks within a chloroplast.

Stroma

The jelly-like fluid within the inner membrane of chloroplasts where captured energy is used to produce carbohydrates.

Light phase (photophosphorylation)

The first step of photosynthesis where light energy is absorbed by chlorophyll, $H_{2}O$ is split, and energy is stored in $ATP$ and $NADPH$.

Dark phase (Calvin cycle)

The light-independent step of photosynthesis where $CO_{2}$ is used to produce $PGA$, which is converted to $PGAL$ and finally glucose ($CH_{2}O$).

Denaturing

The irreversible process where a protein or enzyme loses its three-dimensional structure due to temperatures exceeding its maximum threshold, typically above $45^{\circ}\text{C}$ in plants.

Light saturation

The point at which increasing light intensity no longer increases the rate of photosynthesis.

Cell respiration

A catabolic process occurring 24 hours a day in the mitochondria where complex organic substances are broken down to release energy ($ATP$).

Glycolysis

An anaerobic step in respiration where glucose is split into pyruvic acid to release energy.

Krebs cycle

An aerobic stage of respiration requiring oxygen where a high amount of energy is released.

Fermentation

Anaerobic respiration that produces lactic acid or ethanol and only releases $2\,ATP$ compared to the $36\,ATP$ of aerobic respiration.

Parenchyma

The most abundant plant tissue, composed of thin-walled cells with large vacuoles, functioning in photosynthesis, water storage, and food storage.

Collenchyma

Plant cells with thickened cell walls at the corners, usually found in long strands to offer support to the plant.

Sclerenchyma

Plant cells with even-sided thickening of secondary cell walls caused by lignin; these cells are often 'dead' at maturity and provide strength.

Meristematic tissues

Tissues situated at growth points involved in plant growth or asexual reproduction, where cells reproduce by mitosis.

Apical meristem

Meristem located at the top of the stem (shoot) or bottom of the root where growth in length occurs.

Vascular cambium

Lateral meristem situated in vascular tissues that produces more phloem and xylem, increasing plant girth.

Cork cambium

Meristem that produces cork cells to form bark, providing insulation and preventing water loss.

Xylem

Vascular tissue responsible for the transport of water and dissolved minerals from roots to the rest of the plant.

Phloem

Vascular tissue responsible for the transport of sugars and nutrients in all directions throughout the plant body.

Epidermis

The outside layer of roots, stems, and leaves, often covered by a waxy cuticle above ground.

Root cap

A thimble-shaped group of thick-walled cells that protects the tender root meristem as it pushes through soil.

Adventitious / Fibrous roots

A root system typical of monocots where roots arise from the base of the stem with no single dominant root.

Tap root

A root system typical of dicots where a primary root grows directly downwards with lateral roots developing from it.

Casparian strip

A selectively permeable, impermeable layer in the root endodermis that filters substances entering the vascular bundles.

Transpiration

The evaporative loss of water vapor from the leaf surface through the stomata, which pulls water up from the roots.

Stomata

Pores in the leaf epidermis regulated by two guard cells that allow for gaseous exchange and control water loss.

Photoperiod

The length of uninterrupted darkness that controls the flowering response of many plants.

Osmosis

The movement of water from a dilute solution to a more concentrated solution through a semi-permeable membrane until equilibrium is reached.

Turgid

The state of a cell when the vacuole is swollen with water, exerting pressure on the cell wall and keeping the plant upright.

Active transport

The movement of mineral ions against a concentration gradient using energy ($ATP$).

Chlorosis

A nutrient deficiency symptom characterized by the general yellowing of leaf tissues.

Necrosis

The death of plant tissues, which turn brown and die, caused by severe nutrient deficiencies or environment.

Macro-elements

Chemical elements required by plants in large amounts, including $N$, $P$, $S$, $Mg$, $K$, and $Ca$.

Micro-elements

Chemical elements required by plants in small amounts, such as $B$, $Mn$, $Fe$, $Cu$, $Zn$, and $Mo$.

Phototropism

The plant's growth response to light, where stems usually show a positive response.

Gravitropism

The plant's response to gravity; roots show positive gravitropism (grow down) and stems show negative gravitropism (grow up).

Auxins

Plant hormones that promote cell elongation and apical dominance, found in meristematic regions.

Gibberellins

Hormones that stimulate elongation growth in stems/leaves and work with others to control fruit development and break bud dormancy.

Cytokinins

Hormones that promote cell division, initiate lateral bud development, and prevent senescence.

Abscisic acid (ABA)

The 'stress hormone' that inhibits other hormones and maintains seed and bud dormancy.

Ethylene

A gaseous ripening hormone that controls plant aging, cell wall breakdown, and leaf abscision.