Cell Structure & Function

Discovery of Cells A. History Of Microscopes microscopeThe microscope was developed in the 1600’s, which helped scientists to discover cells. –1. Anton van Leeuwenhoeck lenses pond water describeWas the first to try stacking several lenses together to view tiny objects. He looked at pond water through his lenses. He became the first scientist to describe living cells as seen through a microscope. corkcells monastery. –2. Robert Hooke – used the microscope to examine thin slices of cork. He called the tiny boxes he saw cells. He chose the name "cells" because the chambers he saw reminded him of rooms in a monastery which were called cells.

Cell Theory cell theory.The discoveries and observations that scientists made using microscopes led to the development of the cell theory. The cell theory states….. living thingscells 1. All living things are composed of cells smallest working unit of life 2. Cells are the smallest working unit of life pre-existingcell division 3. All cells come from pre-existing cells through cell division.

cell boundary and DNA.All cells contain a cell boundary and DNA. nucleusThere are 2 Types of cells based on the nucleus –ProkaryotesEukaryotes –Prokaryotes & Eukaryotes Types of Cells

“before nucleus”Prokaryotic = “before nucleus” nucleus membraneProkaryotic cells lack a true nucleus and other membrane bound organelles (internal structures). DNA microscopicsingle celledProkaryotes do contain DNA, usually concentrated in a particular region of the cell. All prokaryotes are microscopic and single celled. Prokaryotes

“true nucleus”Eukaryotic = “true nucleus” truenucleus organelles.Eukaryotic cells contain a true nucleus and other membrane bound organelles. single celled multicellular. specializedEukaryotic organisms may be single celled or multicellular. In multicellular organisms cells become specialized. Eukaryotes

Cell Boundaries There are 2 types of cell boundaries. 1. Cell Membrane 2. Cell Wall

Cell Membrane prokaryoticeukaryotic homeostasis protective barrierEvery prokaryotic and eukaryotic cell is surrounded by the cell membrane. It helps to maintain homeostasis in the cell by functioning as a protective barrier between the cell and its environment. it allows only certain substances inand certain substances out.The cell membrane is selectively permeable which means it allows only certain substances in and certain substances out. plasma membraneA.K.A…… the plasma membrane. fluid carbohydrateslipidsproteins The cell membrane is not a fixed sheet of molecules, but rather it is a fluid structure composed of three biomolecule groups, carbohydrates, lipids, and proteins.

Cell wall Cell membrane

Lipids There are two types of lipids that make up the phospholipidscholesterol cell membrane: phospholipids & cholesterol

Phospholipid Bilayer non-polar polar2 non-polar fatty acid tailspolar headPhopholipids– Phospholipids contain one non-polar end and one polar end. Each phospholipid contains 2 non-polar fatty acid tails and a polar head. bilayertwo "tails"towardheads –The phospholipid bilayer consists of two layers of phospholipid molecules that surround the cell. The non- polar "tails" point toward each other and the polar heads are on the outside forming a sandwich-like membrane.

animal cells onlyCholesterol – Found in the cell membranes of animal cells only to help stabilize them. non-polar fatty acid tailsCholesterol is wedged between the non-polar fatty acid tails of the phospholipid bilayer. Cholesterol

Carbs & Proteins “ID tags”Carbohydrates serve as they are “ID tags” to help identify cells embedded channels pumpsProteins are embedded in the phospholipid bilayer. Their function is to act as channels and pumps in order to transport specific molecules or ions across the cell membrane.

A- Phospholipid Bilayer B – Protein Protein Channel C – Glycoprotein D – Carbohydrate E. Cholesterol

Cell membrane animation

Cell Wall plantsfungi bacteriaanimal cells.Cell walls are the outer most boundary plants, fungi, and bacteria. They are not found in animal cells. structure and support comes in and out The primary function of the cell wall is to provide structure and support. The cell wall does not regulate what comes in and out of the cell. Cell walls of …….. cellulose 1. plants are composed of cellulose chitin 2. fungi are composed of chitin polysaccharides 3. bacteria are composed of other polysaccharides