biology and cell theory
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Biology and Cell Theory
SNC2P
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What is Biology
● Bio: Life● Ology: Study
● In Grade 9 Science you studied Ecosystems & Human activity in your biology unit (the Large picture)
● This year (Grade 10) we will study cells, tissues & organs (the middle picture)
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What is Life?
● How can you tell something is living…..
● Talk to your classmates and brainstorm a list of characteristics that belong to ALL living things.
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Characteristics of Living Things
All living things have common characteristics:
● Require food for energy● Break down food for energy● Limited lifespan● Respond to the environment● Grow● Reproduce● Produce waste ● Are made of CELL(S)
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You are living. Where did you come from?
● Since you fulfill all the criteria for a living organism you are alive.
● If you are alive you are made of cells.
● Where did these cells come from?
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Original Cell Theory
The original Cell Theory, developed mainly in the 1800s, claimed that:
1. All living things are composed of one or more cells.
2. Cells come from pre-existing cells.
3. Cells are the most basic unit of life.
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Modern Cell Theory
The Modern Cell Theory has added several refinements:
● Cells contain DNA (deoxyribonucleic acid) which contains their genetic information and it is passed on each time a cell divides
● All cells are similar with regards to chemical composition and metabolic functions.
● All basic chemical and physiological functions are carried out inside the cell, such as digestion and locomotion.
● Cell activities are dependent upon sub-structures known as organelles.
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Cell Size● Cells are small (1-100µm)
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Cell Surface Area
Cells are small for good reason (transport):
a) Surface-to-volume ratio
b) Distance from surface to centre
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Cell types
Until high school you learn about TWO celltypes.
a) Animal b) Plant
These are important to distinguish.
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Cell Sub-types
● Animal cells are not just of one type (as you have learned to date).
● There are variations that we call specialized cells
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Different types of Animal cells
But there is more to categorizing cellsThere are varieties among animal cells:a) Prokaryotic
Ex: Bacteria cell; no nucleus (or other membrane bound organelles), circular DNA, ribosomes
b) Eukaryotic Ex: YOU are made of Eukaryotic cells; larger, nucleus, linear chromosomes and membrane bound organelles
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Part of a cell - Organelles
● Cells are made up of smaller parts called organelles.
● These organelles perform the functions that the cell needs in order to live, much like your organs do for you.
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Organelles and Cell Structures (Animal)
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Recap
● Cell Theory○ All living things are composed of one or more
cells○ Cells come from pre-existing cells○ Cells are the most basic unit of life
● Cells are made up of smaller parts known as organelles