Bio Notes 1.1
THEMES of BIOLOGY
Biology is the study of all aspects of organisms (living things).
-Earth is full of biodiversity = Many different life forms = increases from poles to equator
-only about 2 million out of estimated 40 million species have been ID’d & studied because they are
very small or live deep in oceans & rain forests
-Life is OLD! Earth is about 4.5 billion years old & life is thought to be 3.5 billion years old- 1st life
was thought to be single celled organisms called Archaebacteria
THEMES OF BIOLOGY
There are 6 themes (main ideas) : (CHEEER)
CELLS -the cell’s structure determines function
HOMEOSTASIS & Stability- systems want to stay same
EVOLUTION- species have adaptations & change over time
ENERGY, MATTER & ORGANIZATION – organisms use energy to organize the material in their body
ECOLOGY – all things, living & nonliving, are related and depend on each other
REPRODUCTION- have to pass DNA & traits on to offspring in different ways
CELLS
-All living things are made of CELLS- The CELL is the basic unit of structure & functions of life !
-All cells are different because their structure is related to their function
-Morphology – study of form or structure
-Some organisms are:
Unicellular – made of 1 cell –-reproduce asexually - offspring IDENTICAL to PARENT
Multicellular – has many cells-- reproduce sexually offspring are DIFFERENT from PARENTS
2 Types of Cells:
Prokaryotic: Cells that DON’T HAVE a nucleus & organelles with a membrane (ONLY BACTERIA)
Eukaryotic: Cells that HAVE a nucleus and organelles with a membrane (ALL OTHER ORGANISMS)
All cells have these in common:
-Cells have a protective membrane! (all cells have a membrane, not all have a wall)
-Cells have the INSTRUCTIONS (DNA) for all structures and functions!
-Cells have little ‘organs’ (organelles) in them to perform all functions to keep them alive
CELL DIFFERENTIATION
-cell differentiation: process by which cells become different, multiply and carry out different functions
-All cells start out EXACTLY the same but become different as they develop
Types of Cells --Bone cells, skin cells, muscle cells, blood cells, sex cells
HOMEOSTASIS & STABILITY
All living things have to maintain a stable level of conditions inside their body!
Homeostasis- the stable level of internal conditions
Examples
- you get hot – you SWEAT–you get cold– you SHIVER!
- Seals have thick fat layer to insulate & lots of blood vessels in flippers that regulates heat flow
(blood carries heat – like blushing makes your face hot)
Body works on a feedback system: a chain or loop where
-positive feedback: a feedback loop that accelerates a process
-negative feedback: a feedback loop that slows down a process
A
B
(has NOTHING to do with “good” or “bad” outcomes)
Positive example: embarrassed = you blush = more embarrassed = more blushing
Snow melts = dark ground exposed = more snow melting = more dark ground
showing
Negative example: hot = sweat = you cool down
Cold = shiver = you warm up
Most body systems are negative feedback loops
EVOLUTION
-Evolution –theory that species (not the individual) change over time (Evolve means ‘to change’ )
-This is the UNIFYING THEME of biology!!!
-evolution happens through natural selection and competition
-phylogeny – the study of the evolutionary history of an organism (how it’s changed over time)
NATURAL SELECTION
-This is the ‘survival of the fittest’ idea---nature picks those with best traits to survive!
-Organisms have good and bad TRAITS (characteristics) –- good ones = long life = many offspring with
good traits, bad ones = short life = few offspring so bad traits aren’t passed on
-adaptations – TRAITS or behaviors that help them survive better
-Over many generations the organism EVOLVES due to nature selecting the best traits!!
Natural Selection =PROCESS by which organisms with better adaptations live longer & pass them
on to their offspring
Adaptation = a favorable TRAIT than increases an organism’s chance of survival
Evolution =THEORY that species change over time because nature picks organisms with best
adaptations for their environment and they live and pass those traits on
ENERGY
ALL living things need energy! All energy ultimately comes from the SUN!!
Plants photosynthesize to make energy, animal/humans eat plants or other animals to get energy
Autotroph (producer)– organisms that make their own food (energy) and are basis of food chain –
-plants and bacteria
Photoautotroph- Organism that uses light to make its own food by photosynthesis
Photosynthesis – Conversion of light into chemical energy in an organism
( light)
6 CO2 + 6 H2O
Carbon dioxide + water and

C6H12O6 +
light making glucose
and
6 O2
oxygen
Chemoautotroph –Organism that uses chemicals to make its own energy (food)
Heterotroph (consumer)- organisms that get food from other organisms/plants
Cellular respiration: Process by which cells make ATP by breaking down organic compounds
(organic compounds are compounds that contain carbon)
C6H12O6 +
Glucose (fuel) +
6 O2
oxygen
--->
produces
6 CO2 +
carbon dioxide
6 H 2O +
water
ATP
and energy
ECOLOGY – Interdependence of Organisms!! (organisms depend on other organisms)
-Ecology = the study of the interactions of organisms with each other & environment
-Environment made of 2 parts:
-biotic factors = living parts
-abiotic factors = non-living parts
Biosphere: Large- the part of the earth where all life exists
-ecosystems – Environmental communities made of living & nonliving parts
Communities – All the living things in an area (all the deer & rabbits, & people, etc)
-population = all of one type of organism (all the deer; all the rats; all ants)
-organism – simplest level- includes just 1 organism
When we study ecology we see that EVERYTHING is connected somehow! If one part gets
messed up- it will affect other things! No organism is solitary!
REPRODUCTION & INHERITANCE
Reproduction: The production of offspring
DNA- The Instructions For YOU!!!
DNA –genetic information , the ‘Blue-print”- for YOU- in every cell- coiled up in your
chromosomes
Genes – Short pieces of DNA that have a chemical “code” or instructions for proteins
that create every structure and function in your body, every trait
-DNA is like a big library and each book is a gene
-You read only the books you want, your cells use only the genes they need
-Every cell has ALL the genes, not all are used for that cell, you go to a library that
has ALL the books, but you don’t read them all
2 Types of Reproduction!
Sexual Reproduction
-Gametes from 2 different organisms (or one organism) is joined to produce offspring
- Gametes – sex cells (egg & sperm)
-Female sex cell (egg) & male sex cell (sperm) join -DNA from them is combined to
make offspring that are DIFFERENT from parents
-Zygote – fertilized egg created by joining the egg & sperm
Asexual Reproduction
Takes only 1 organism – egg & sperm not joined, its own DNA is copied
Offspring are IDENTICAL to parents – NO evolution, natural selection, or adaptations!
Most common types are:
Fission: an organism duplicates its DNA and splits in 2 creating 2 identical organisms
Budding: parent grows a bud, from which a smaller form of the adult grows & separate
Fragmentation: a piece of a parent regenerates into an entirely new organism
INHERITANCE – Getting traits from parents!
Traits are mixed & inherited from parents & creates DIVERSITY of LIFE!! Hopefully with new traits that
will make the species successful and able to compete better
Gene Activation
-A caterpillar & butterfly are the same organism- but they look different because at
different times in life, different genes are ‘expressed’ or ‘turned on’.
-Beneficial because there is less competition- they eat different things
Oncogenes- genes that when “turned on” or “expressed” cause cancer