Basics of Biology

Chapter 4

Name one difference between a plant cell and

an animal cell

What is the purpose of a cell membrane?

What type of cells do we have? A) Prokaryotic B) Eukaryotic

Do Now

SWBAT: Identify levels of organization

from cell to ecosystem

Describe the challenges that marine organisms face living in the sea

Describe the process of osmosis and determine what makes active transport different from passive transport.

Objective

All living organisms can be divided into two

basic groups based on cellular composition:

1. Prokaryotic2. Eukaryotic

Types of Organisms

Prokaryotic Organisms:

Lack a nucleus Posses ribosomes Contain a circular ring of DNA Some may also have plasmids, extra pieces of

DNA Cell wall is normally present May have a flagellum Unicellular

Types of Organisms

Eukaryotic Organisms

Possess DNA enclosed inside a nucleus Posses many specialized organelles (look at

organelles in Fig. 4.8) Eukaryotic organisms can be unicellular or

multicellular

Types of Organisms

Atom – fundamental unit of all matter

Molecule – two or more atoms chemically joined together

Levels of Organization in Living Organisms

Organelle – specialized features of cells

Cell – basic unit of life

Levels of Organization in Living Organisms

Tissue – group of cells functioning as a unit

Organ – many tissues arranged into a structure with a specific purpose in an organism

Levels of Organization in Living Organisms

Organ system – group of organs that work

together

Whole organism (individual)

Levels of Organization in Living Organisms

Interactions among individuals

Population- A group of organisms of the same species that occur together

Example

Interactions among individuals

Community- all the populations in a particular habitat

Example

Interactions among individuals

Ecosystem- A community of communities in a large area, together with their physical environment

Ecosystem

Planktonic organisms (drifters) Benthic organisms (bottom dwellers) Nekton (strong swimmers)

Many adaptations are made to maintain internal body conditions Homeostasis

Challenges of life in the sea

Enzymes and organic molecules are sensitive

to ion concentration Diffusion and Osmosis

Salinity

In solution- ions & molecules move around like

water molecules

Random movement spreads them out until they are evenly distributed.

Result: molecules move from areas of high concentration to low concentration

Diffusion

Internal composition differs from external in

the cell- substances will move into or out of the cell by diffusion

If more sodium in outside the cell – sodium will diffuse into the cell Problem if organism is sensitive to sodium

Diffusion and cells

Since marine organisms live in a very solute-

rich environment, they have a tendency to gain solutes and lose water

This can result in the death of cells if the water loss/solute gain is significant

These organisms must find ways to deal with this diffusion and osmosis

Diffusion and Osmosis

Membrane blocks the passage of the common

ions in seawater and many organic molecules.

Membrane allows exchange with many molecules such as O2 and CO2

Selectively permeable – only some substances enter and leave

Membrane barrier

If the solutes are higher outside of the cell

than inside of the cell, water will rush out of the cell. Cell will shrink

http://www.youtube.com/watch?v=sdiJtDRJQEc

Discovery Ed simulation

Osmosis

The movement of water across a selectively

permeable membrane

If the total concentration of solutes inside a cell is higher than the outside the cell, water will rush into the cell. Cell will swell

Osmosis

Proteins in the cell membrane pump materials

in the opposite direction to which they would move by diffusion.

Requires energy What form is that energy in?

How often do we use active transport? Over 1/3 of a cells total energy expenditure

Active Transport

What is needed to move molecules into or out of a cell against the gradient?

What are cell membranes made of?

What is imbedded in the cell membrane?

ATP has “trapped” energy from what process?

Active transport brings in materials to the cell and what else does it do?

Discovery ed Simply Science: Matter and Energy on the move active transport

Active Transport

Some marine organisms do not actively

maintain salt and water balance Salinity changes with salinity of water –

Osmoconformers

Regulation of Salt and Water Balance

If an osmoconformer were placed in a

freshwater environment, the would swell and burst. Water would rush into the cell because water

would move into the cell (low concentration) Open ocean is where you find osmoconformers

Osmoconformers

Adjust solutes in your body to match solutes of

water outside the body. Total amount of dissolved material needs to

be the same Change the amount of one particular chemical

to match changes in salinity outside Sharks- increase/decrease urea in their blood Danasliella-single celled marine alga –

changes glycerol

Ways to adapt

Osmoregulation fresh vs marine

Marine birds, reptiles and plants have special

cells or glands to get rid of extra salts.

Marine plants have cell wall to help regulate swelling caused by osmotic water gain

Osmoregulation

Vocab

What is the difference between osmosis and

diffusion

How do marine fishes deal with the the water they constantly loose to the salty environment they live in?

What is a population?

What is a community?

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