The structure of living beings

• Title: L'estructura dels éssers vius
• Cells are the basic components of living beings, similar to how bricks and beams form a house
• The cells contain diminutive compartments

Cell Parts

• Parts of the cell include organelles, ribosomes, mitochondria, cytoplasm, cell membrane, and nucleus

Basic Cell Structure

• The cell membrane acts as a thin envelope that protects the cell and allows the exchange of substances with the outside
• The cytoplasm is a gelatinous material composed of water and dissolved substances
• Organelles within the cytoplasm perform various functions; for example, mitochondria produce energy, and ribosomes synthesize proteins
• The coordinated function of organelles ensures the cell's survival
• The nucleus is an organelle that contains the cell's genetic material and directs cellular activities

Cell Types

• Eukaryotic cells have a nucleus, while prokaryotic cells do not

Cell Sizes and Shapes

• Prokaryotic cells are the smallest cells
• Within eukaryotes, plant cells are larger than animal cells
• Animal cells vary in shape (spherical, star-shaped, elongated), while plant cells tend to be prismatic or polygonal

Plant Cells

• Plant cells have a rigid outer layer called the cell wall, which surrounds the cell membrane
• Plant cells contain a large, fluid-filled vacuole and green organelles called chloroplasts, which contain chlorophyll

Prokaryotic Cells

• The majority of prokaryotic cells are bacteria
• Bacteria have a rigid outer covering called the bacterial wall, which surrounds the membrane and causes some bacteria to produce diseases

Prokaryotic Cell Structure

• Prokaryotic cells consist of a thin cell membrane and cytoplasm

Unicellular vs. Multicellular Organisms

• Most living beings are multicellular, made of millions of cells.
• Unicellular beings can live independently

Multicellular Organisms

• The cells need to work together to survive
• Cells are organized and coordinated

Tissues

• Cells with the same structure and function group together to work in a coordinated manner.
• These groupings form tissues

Animal Tissues

• Epithelial
• Bone
• Muscle
• Nervous

Plant Tissues

• Protective
• Support
• Conductive

Organs

• Organs are formed by coordinated tissues.
• In animals examples include: lungs, heart, stomach
• In plants examples include: flower, leaf, stem, and root

Systems

• Systems are coordinated organs that work together to perform a specific function, with each organ performing its specific role

Vital Functions

• These include nutrition, reproduction, and interaction

Classification of Living Matter

• Nivells de classificació de la matèria viva

Viruses

• Viruses are much smaller than bacteria and are not considered living beings because they only perform the vital function of reproduction
• They are simple entities that need to reproduce inside the cells of a living being

Virus Reproduction

• Virus kills the cells they attack which causes diseases
• In animals it can cause rabies
• In plants it can destroy leaves and fruits

Bacteria

• Bacteria are unicellular prokaryotes and the simplest living beings
• They live everywhere

Bacteria Nutrition

• Some bacteria are autotrophs, meaning they produce their own food
• Most bacteria are heterotrophs, feeding on other living beings or dead matter, acting as decomposers
• Certain bacteria cause diseases, some live in our intestines helping with digestion, and some are used in industries

Complex Unicellular Organisms

• Includes protozoa, which are unicellular eukaryotes that live in water or inside other living beings
• They are heterotrophs, feeding on bacteria and other protozoa

Unicellular Algae

• Also exist, and are eukaryotes that live afloat in fresh or salt water
• They belong to a community known as seston and are autotrophs

Fungi

• Fungi are eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds and mushrooms)
• Multicellular fungi have a part called mycelium, formed by microscopic filaments called hyphae

Fungi Nutrition

• Fungi play an important role in nature by decomposing dead plant and animal matter

Protozoa

• Can exist and are of different types

Amoebas

• Are unicellular and consist of a single cytoplasm with different organules - including vacuoles

Amoeba Movement and Nutrition

• They move with parts growing from their membrane acting as false feet
• This enables them to slip on watery surfaces which they also use when feeding/capturing food
• Some amobas are parasitic whilst some move feely in watery surroundings

Types Protozoa

• These feed on :bacteria; plants: microscopic animals, other protozoa

Paramecia

• Are also unicellular with an oval shape
• Their case is covered in thin tiny extensions named cilia

Paramecia Movement and Nutrition

• The cilia enable them to swim freely in fresh water
• Are generally common in stagnant watery surroundings
• They feed; bacteria, algae, yeasts

Vorticelles

• These are fresh water unicellular protozoa
• Their body looks campaniform and they stick via peduncle on surfaces they can easily live on
• They feed on bacteria with their cilia uptop