Chapter 22 part 1
The Basic Unit of Life – the Cell
The Big IdeaAll living things are made up of one
or more units called cells
Biology: the study of Life
 Biology is the study of life and
living things
 A biologist is anyone who uses
the scientific method to study life
 An organism is an individual
living thing such as a plant or an
animal.
Branches of Biology- most of
these overlap with other fields
 Zoology- study of animals
 Botany- study of plants
 Microbiology- study of small microscopic organisms
 Paleontology- study of extinct organisms
 Cytology- study of cells
 Genomics- study of the total hereditary content of various
organisms
There are a lot more branches and sub-branches
But what exactly makes a
living thing alive?
https://www.youtube.com/watch?feature=player_embedd
ed&v=juxLuo-sH6M#t=0
Characteristics of Living
Things
 Are made up of one or more units called cells
 Are based on a universal genetic code
 Obtain and use energy
 Grow and develop
 Maintain a stable environment
 Reproduce
 Respond to their environment
 Evolve
1. Living things are made
up of cells
 Cell- basic unit of structure and function in
living things; though small in size, cells are
complex and highly organized
 Organisms are of two types:
 Unicellular- an organism consisting of a single
cell; bacteria, protists, some fungi
 Multicellular- an organism consisting of many
cells; some of which are typically specialized for
particular functions
2. Living things are based
on a universal genetic code
 All organisms store the complex information they
need to live, grow and reproduce in a genetic code
written in the molecule DNA (deoxyribonucleic
acid)
 That information is copied and passed from parent
to offspring
 With a few minor variations, life’s genetic code is
almost identical in every living organism on earth
3. Living things obtain and use energy
the energy is conserved and changed from
one type of energy to another
 Autotroph- organism that makes it’s own
food for energy (producer)
 Photosynthetic autotroph- uses sunlight as its
energy source to make food (photosynthesis)
 Chemosynthetic autotroph- use the energy
from chemical reactions as its source of
energy to make food ( obscure group)
 Heterotroph- organisms that get their food
from an outside source- cannot make it
themselves- use the processes of cellular
respiration and fermentation to release
energy from food (consumer)
 Chemotrophic heterotroph- organisms that can
obtain energy by taking in organic molecules
and then breaking them down
 Phototrophic heterotroph- organisms that are
able to use sunlight for energy but also require
organic compounds for energy (obscure group)
Other important terms here:
Metabolism- the sum total of all the chemical
reactions in the body – the balance of catabolism
and anabolism
Catabolism- the final breakdown of complex
substances to simpler substances
Anabolism- any process in a living organism
that involves putting together, or synthesizing
complex substances from simpler substances
4. Living things grow and
develop
 Growth can be accomplished in two
ways:
 Increase in cell size (baby cell grows
bigger)
 Increase in cell number (for multi-cellular
organisms)
 Development involves maturation
 A butterfly goes through a metamorphosis
to change from a egg, to larva, to pupa to
butterfly
 Female egg cells mature during
menstruation
 Organisms have some type of life cycle
that takes them from birth to death- some
are more complicated than others but all
living things have them
5. Living things maintain themselvesthey maintain a stable environment
 They make structures and repair
damaged structures
 They maintain their internal
environment
 Using energy to keep conditions inside
their cells within certain limits is called
homeostasis
More on maintaining
environment
 Def- homeostasis- an organism’s
ability to maintain constant or
stable conditions that are
necessary for life
 Ex- sweating or shivering to
maintain temperature; blood
pressure, etc.
6. Living things can
reproduce as a species
 Reproduction- producing new organisms of the
same type
 Asexual reproduction- a single organism produces
new organisms that are genetically identical to itselfbacteria, protists, fungus, plants, some animals
 Sexual reproduction- a process in which two cells,
normally from different organisms unite to produce
the first cell of a genetically different organism –
bacteria (simple) protists, fungus, plants, animals
7. Living things can respond
to their environment
 Responses can be rapid or slow
 Stimulus- anything in the environment
that causes an organism to react
 Irritability- no, not grumpiness!- it’s
the ability of an organism to respond
to stimuli (plural of stimulus)
8. Taken as a group, living
things evolve
 Over generations, groups of organisms
evolve, or change over time
 Evolutionary change links all forms of life to
a common origin more than 3.5 billion years
ago
 Evidence of this shared history is found in all
aspects of living and fossil organisms, from
physical features to structures of proteins to
sequences of information in DNA.
More on evolution
 Any structure, behavior or internal
process that enables an organism to
respond to environmental factors and
live to produce offspring is called an
adaptation
 Adaptations are inherited from previous
generations
 The gradual change in a species through
adaptations over time is evolution
Review

Are made up of one or more units called cells

Are based on a universal genetic code

Obtain and use energy

Grow and develop

Maintain a stable environment

Reproduce

Respond to their environment

Evolve

http://www.mybigcampus.com/library/108935