cells: the basic units of life section 1: the diversity of cells
TRANSCRIPT
What is a cell? The smallest unit that can perform all the
processes necessary for life.
Brainstorm with your neighbor what you think some of those processes are?
Why do you think cells weren’t discovered until the mid-1600’s
Answer: That was when the microscope was invented.
Possibilities: growing, reproducing, taking in nutrients, getting rid of waste, performing specialized functions (heart cells, nerve cells)
Scientists who first discovered and defined cellsFirst person to describe cells
First person to discover single-celled organisms, different blood cells and bacteria.
People who wrote the 3 parts of the cell theory
Robert Hooke
Anton van Leeuwenhoek
Schleiden/Schwann/Virchow
The Cell Theory All organisms are made of cells
The cell is the basic unit of all living things
All cells come from existing cells
Cell Size Most cells are small.
Big cell example: chicken egg yolk The surface area-to-volume ratio limits size
If cell volume is too big then the surface area will be too small for sufficient nutrient and waste transfers.
Equation: Surface area ÷ volume
Challenge question: What is the surface area-to-volume ratio of a cube whose sides are 2 cm long?
Cell parts All cells have the following even though
they have different functions and different shapes
1) Cell Membrane2) Cytoplasm3) Organelles4) Genetic material
Cell Membrane & Cytoplasm Cell Membrane
Protective layer that covers the cell’s surface
Acts as a barrier Controls materials going in and out of the
cell Cytoplasm
The fluid inside the cell
Organelles Structures that have specific functions
in the cell. Different types of cells have different
organelles Examples: nucleus, ribosomes,
mitochondria, endoplasmic reticulum, chloroplasts
Genetic Material All cells have DNA (deoxyribonucleic acid)
Genetic material passed from parent to new cells
Contains information needed to make new cells
Controls the activities of the cell Is enclosed in the nucleus is some cells
Prokaryotes Two groups
Eubacteria(or just plain bacteria) Most common World’s smallest cells
Archaebacteria Same in many ways to bacteria Some organelles are different Can live where no other
organism can (hot springs or deep ocean volcanic vents)
Eukaryotes All living things that are not prokaryotes
are eukaryotes Are the largest cells (10x larger than
bacteria) Have a nucleus Can be single-celled organisms
Examples: amoebas and yeasts Often are multicellular organisms
Examples: animals or plants
Review question 1Who was the first person to describe cells?
A) Louis Pasteur
B) Charles Darwin
C) Robert Hooke
D) Isaac Newton
Review question 2Which of the following is NOT part of the cell theory?A. All organisms are made of cells
B. The cell is the basic unit of all living things
C. All cells are the same shape
D. All cells come from existing cells
Review question 3Which cell part acts as a protective barrier?
A. Cell Membrane
B. Cytoplasm
C. Organelles
D. Genetic material