Cell Structure: Plant vs Animal cells

• Objectives covered are Sec A, 1.1-1.4

Cell

• A cell is the basic unit of life
• A cell is the building block of all living things
• Unicellular organisms consist of one cell, for example, bacteria
• Multicellular organisms consist of many cells

Plant Cell vs Animal Cell

• Cell membrane: present in both
• Cell wall: present in plant cells, absent in animal cells
• Cytoplasm: present in both
• Nucleus: present in both
• Ribosome: present in both
• Vacuole: large and permanent in plant cells, small and temporary in animal cells
• Starch grains: almost present in plant cells, absent in animal cells
• Glycogen granules: absent in plant cells, present in animal cells
• Chloroplast: present in plant cells, absent in animal cells

Organelles

• The parts inside of a cell are called organelles

Cell Membrane

• Composed of a phospholipid bilayer with 2 layers made of protein and fat
• Surrounds the cell
• Controls what enters and exits the cell and is selectively permeable

Cell Wall

• Made up of a rigid material called cellulose
• Provides structural support for the plant cell, preventing it from bursting
• Is freely permeable, allowing all materials to pass through

Cytoplasm

• A jelly-like substance
• Mainly composed of water and other dissolved substances
• Where many metabolic reactions take place

Nucleus

• Often referred to as the "brain" of the cell
• Controls all of the cell's activities
• Contains the genetic material of the cell, called DNA

DNA

• Deoxyribonucleic acid
• Found on structures called chromosomes
• Chromosomes are only seen during cell division

Mitochondria

• Rod-shaped structures with folded inner membranes
• Often referred to as the "powerhouse" of the cell
• Where cellular respiration mainly takes place
• Cellular respiration is the production of energy from food

Ribosome

• Structure made up of 2 units
• Responsible for producing proteins

Vacuole

• Fluid-filled sac
• Contains a mixture collectively known as cell sap
• Helps maintain water balance in plant cells
• Keeps the plant cell turgid

Chloroplast

• Sac-like organelle with membranes stacked inside
• Contains chlorophyll needed to trap light to produce food during photosynthesis

Starch Grains

• Food storage in plant cells

Glycogen Granules

• Food storage in animal cells

Cell Specialization/Differentiation

• Cells can change and become specialized, developing different structures suited to particular functions
• Cells specialize for 2 main reasons: division of labor and efficiency

Specialized Cells

• Muscle cell: numerous mitochondria to produce energy to do work
• Nerve cell: long axon to transmit impulses
• Blood cell: hemoglobin to transport oxygen
• Sex cell: half the number of chromosomes

Cell Grouping

• Cells form tissues; tissues form organs; organs form systems; systems form an organism
• Tissue: group of specialized cells working together to carry out one specific function, e.g. blood, palisade in plants
• Organ: group of tissues working together to carry out one specific function, e.g. skin, liver, heart, kidney
• System: group of organs working together to carry out one specific function, e.g. circulatory, nervous, digestive
• Organism (multicellular): group of systems working together to achieve life