Cell Structure and Function Unit 4

What is a cell? Cells are the basic units of life. Muscle Cells Nerve Cells

In 1665- Robert Hooke examines a slice of cork under a compound microscope and sees empty chambers he calls “cells”. Next Anthony van Leeuwenhoek uses a single lens microscope to view pond water and sees tiny living organisms in the water!

In 1838 Mattias Jakob Schlieden concludes that all plants are made of cells. One year later in 1839 Theodor Schwann concludes that all animals are made of cells.

Rudolf Virchow New cells come from existing cells

These discoveries lead to… Cell theory which states- All living things are composed of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells

Modern Cell Exploration Today scientists still study cells but they have better tools to do so. Flourescent Labels- enable scientists to track molecules throughout the cell

From cell to organism A cell is the basic unit of life, from which larger structures such as tissue and organs are made. All living things are made up of cells. The appearance of each living thing is the result of the types of cell that it is made up of and how these cells are organized. Photo credit (left): © 2009 Jupiterimages Corporation Photo credit (right): © 2009 Jupiterimages Corporation

Types of Cells Prokaryotic (Prokaryote) Eukaryotic (Eukaryote)

Similarities All cells have 2 things in common: They are surrounded by a cell (plasma) membrane They contain DNA, the molecule that carries biological information, at some point in their life Both

Differences Prokaryotes Eukaryotes DNA not contained in nucleus Karyon means kernal in Greek Pro means before, therefore these cells evolved before nuclei were developed Generally less complicated Example: bacteria Eukaryotes DNA contained in a nucleus Karyon means kernal in Greek Eu means true suggesting that these cells do have nuclei Generally more complicated Examples: plants, animals, fungi and protists

Specialized cells Most plants and animals are multicellular. The human body is made up of around 200 different types of cells, all working together. Most cells are specialized, meaning that each type of cell has a specific structure and function. All cells with a nucleus contain the same genes, but different cells activate different genes so they only produce the proteins they need. Photo credit: © 2007 Jupiterimages Corporation Cross section of the leaf from a Dianthus (carnation) plant. Image shows epidermis, spongy and palisade cells. Teacher notes Red blood cells are an example of a type of cell which has no nucleus. Gametes (such as egg cells and sperm cells) only have half a full set of genes. However, all cells have certain common features and structures called organelles.

Organelles are structures within cells which contribute to the overall function of the cell. Organelle means “little organ” Nucleus Cytoplasm