Gr.10 Bio (Organelles)

Cell

Smallest unit that can perform the functions of life.`

Prokaryotic vs eukaryotic cells

Eukaryotic

• Nucleus

• DNA is in chromosomes

• Genetic info is inside a membrane-bound nucleus

• Has membrane-bound structures like mitochondria, golgi apparatus

• Mitosis and meiosis

• Multicellular or unicellular

Prokaryotic

• No membrane bound nucleus; dna is in a region called the nucleoid

• DNA is circular

• Genetic info is bundled up into a section of the cell called the nucleoid(not membrane-bound)

• Lacks membrane-bound organelles

• Binary fission(asexual reproduction)

• Always unicellular

Cell Theory

1. All living organisms are made of one or more cells (and their products)

2. The cell is the simplest unit that can carry out life processes

3. All cells come from pre-existing cells; they don’t come from non-living matter

Organelles

• Specialized structure in a cell.

• Perform specific cell processes needed for a cell to live

Cell processes

• Use energy

• Store materials

• Absorb materials

• Eliminate waste

• Transport substances

• Reproduce

Cell Membrane/Plasma membrane

• Flexible membrane that surrounds all cells

• Made of phospholipid(which also form the membranes around organelles)

• Controls exchange of material between interior of the cell and external environment.

• Protection and cell shape

• 2 methods for materials to cross cell membrane:

  • Diffusion: spreading of molecules from an area of high to low concentration.

  • Osmosis: movement of water thru a semi-permeable membrane from area of high to low concentration

Cytoplasm

• Contains the cytosol and organelles in the cell membrane

  • Cytosol: flulid material between cell membrane and nucleus

• Mostly made of water and can range from liquid to jelly-like substance

• Cell organelles are suspended in the cytoplasm

Nucleus

• Contains nucleolus & surrounded by nuclear membrane/nuclear envelope

  • Nuclear membrane is double layered and has pores

• Control center of cell

• Contains genetic info (chromosomes)

Nucleolus

• Darker area in the nucleus

• Where ribosomes are made

  • Ribosomes make protein

Endoplasmic Reticulum

• Network of flattened interconnected membrane sacs(tubes/pockets)

• Branches out from nuclear envelope

• Smooth ER

  • No ribosomes on its membrane surface

  • Site for lipid synthesis

• Rough ER

  • Contains ribosomes on its membrane surface

  • Site for protein synthesis

Ribosomes

• Made in nucleolus

• Can be found bound to the rough ER or floating freely in the cytoplasm

• Functions to catalyze the reactions of protein synthesis

reason for mitosis

• Maintain SA:V ratio

• Replace damaged cells

• Growth

Golgi body/Golgi apparatus

• Flattened, stacked, interconnected membrane sacs

• Located near ER

• Process materials to be removed from the cell

• Packages products into vesicles for transport

Mitochondria

• Double membrane

  • Inner membrane: folded to increase SA; reactions occur on inner membrane

• Produces energy through CELLULAR RESPIRATION

  • glucose + O2 —> CO2 + H2O + energy

• Active cells —> more mitochondria

  • Muscle cells

• Inactive cells —> less mitochondria

  • Fat cells

Centrioles

• Comes as a pair

• Made of cylindrical tubes

• Involved in cell division by organizing spindle fibers during mitosis

Vacuole

• Fluid filled sac surrounded by a single layer of membrane

• Animal cells: many small vacuoles

• Plant cells: central vacuole

• Storage of food, water, waste

• Removes unwanted substances from cell

• IN PLANTS

  • Maintains internal fluid pressure which helps give plants structure + strength

Cell Wall

• PLANT CELLS ONLY

• Found outside cell membrane

• Rigid, porous

• Made of cellulose

• Gives shape + protection

C

Chloroplast

• Double membrane

• Contains chlorophyll(pigment that gives plants their green colour)

• Site for starch(sugar) storage

• Site for photosynthesis

  • CO2 + H2O + energy —> O2 + glucose

Cytoskeleton

Filaments and tubules that provide a framework to the cell, helping maintain its structure and providing “tracks” along with vesicles and organelles that can moveVe

Vesicles

• Membrane-covered sacs that transport and store materials inside the cell

• Helps these materials cross the cell membrane as they enter/exit cell

Lysosomes

• Single membrane

• Cell’s recycling center —> breaks down waste and celluar debris through enzymes.

DNA

• Material found in the cell nucleus that contains genetic information and the blueprint of how to build a cell.

• Contains thousands of genes

  • Genes: a segment of DNA that controls protein production

  • DNA exerts control through genes, determining what kinds of protein your cells can make, and therefore how your body will function/look.

• “Code for protein” - Mr.Suteir

Chromosomes

In a cell nucleus, a thread like structure mostly made of DNA

Enzymes

• Catalyze(speed up) various chemical reactions

  • Eg. digesting food

Down syndrome

Chromosome 21 —> individuals have 3 chromosomes instead of 2

Mutation

• Caused by mutagens(forces/substances that physically damage DNA)

• A change in the usual order of the A, C, T, G building blocks.

• A mutation can alter the structure of the protein it produces.