MRS GREHN and structures + functions of living organisms

Name the 8 characteristics all living organisms share

Name the 8 characteristics all living organisms share

1. nutrition

2. respiration

3. excrete waste

4. respond to their surroundings

5. move

6. control internal conditions

7. reproduce

8. grow and develop

Eukaryotic organisms

multi-cellular or single -cellular organisms

consist of cells with a nucleus and distinct membrane

• plants

• animals

• fungi

• protoctists

plants

• contain chloroplasts (photosynthesis)

• cellulose walls

• store carbohydrate as starch or sucrose

animals

• store carbohydrates as glycogen

• nervous coordination

• able to move from place to place

fungi

• cell walls made of chitin

• some are single celled (eg. yeast)

• body organised into mycelium, made from hyphae, containing many nuclei.

• feed by excreting extra cellular digestive enzymes onto the food and absorb digested molecules (saprotrophic)

• store carbohydrates as glycogen

• some fungi are parasitic (feed on living material)

protoctists

• microscopic, single-celled organisms

• usually aquatic (eg. amoeba)

• some have animal cell features (eg. plasmodium and amoeba - causes malaria)

• some have plant cell features (eg. chlorella)

Prokaryotic organisms

cells don’t have a nucleus (DNA in cytoplasm)

single-celled organisms

• bacteria

Bacteria

• single-celled (have different shapes)

• cell wall, cell membrane, cytoplasm, plasmids.

• no nucleus. have circular chromosome of DNA in cytoplasm

• some photosynthesize.

• majority feed off of living/dead organisms.

examples of bacteria

• Lactobacillus: a rod-shaped bacterium used in the production of yoghurt.

• Pneumococcus: a spherical bacterium that acts as the pathogen causing pneumonia.

Pathogen

microorganisms that cause disease

• fungi

• bacteria

• protoctists

• viruses

Viruses

• viruses are pathogenic and only exist inside a living cell.

• very small particles (various shapes)

• protein coat surrounds DNA or RNA.

• live + reproduce only in living cells

• can reproduce and infect every living organism (by instructing host cell to make more of them)

  do not carry any other characteristics of a living organism

describe the levels of organisation in organisms

1. organelles

2. cells

3. tissues

4. organs

5. organ systems

organelles

tiny structures within cells

eg. nucleus, ribosomes, chloroplasts

tissues

a group of similar cells working together to perform a specific function

eg. xylem tissue

organs

a group of different tissues working together to perform a function

eg. lungs

organ systems

lots of organs doing a different job to achieve one function

eg. digestive system, respiratory system

nucleus

• contains genetic information of the cell

• DNA forms the chromosomes

• chromosomes are thread-like structures

cytoplasm

• gel-like substance

• contain enzymes, which catalyse metabolic reactions (eg. protein synthesis and respiration)

• organelles float in cytoplasm

cell membrane

• out surface of cell

• controls movement of substances in/out of cell (via diffusion and active transport.)

cell wall

• rigid cellulose structure (surrounds outside of cell membrane)

• maintains shape of cell

mitochondria

• site of aerobic respiration

chloroplasts

• contains green pigment - chlorophyll

• the site of photosynthesis

ribosomes

• synthesizes proteins

vacuole

• large organelle that contains cells sap

• gives cell rigidity

organelles in animal cells

• nucleus

• cell membrane

• cytoplasm

• mitochondria

• ribosomes

organelles in plant cells

• nucleus

• cell membrane

• cytoplasm

• mitochondria

• ribosomes

• chloroplasts

• cell wall

• vacuole

what is cell differentiation?

Process by which cells become specialized to perform a specific function within an organism.

what are stem cells?

Cells that have not undergone differentiation and is not yet specialized.

examples of specialized cells (4)

• root hair cell - elongated root hair cell increases surface area for absorption

• guard cells - shape alters when turgid/flaccid. controls opening of stomata.

• red blood cells - no nucleus. more space for haemoglobin to carry oxygen.

• nerve cells - elongated nerve fibre transmits nerve impulses.

adult stem cells

medicine already uses adult stem cells to cure disease…

can only develop into limited number of cell types

• bone marrow

• liver

• heart

embryonic stem cells

can develop into any cell type

advantages to using stem cells in medicine

• can treat currently un-curable disease.

• eg. stem cells from bone marrow of a healthy person → replace faulty blood cells in a patient.

• eg. embryonic stem cells made into nerve cells for people paralyzed with spinal injuries.

disadvantages of stem cells in medicine

• stem cells grown in lab may become contaminated with a virus, passed onto the patient.

• human embryos destruct a potential human life.