year 11 bio.docx

MOD 1

Modern cell theory

• The cell is the smallest living unit in all organisms.

• All living things are made up of cells.

• All cells come from other pre-existing cells

3 Domains of life

• Bacteria

• Archaea

• Eukarya

- > Eukarya may be protists, plants, animals, or fungi,

M ovement

R espiration - make energy

S ensitivity - respond to stimuli

G rowth

R eproduction

E xcretion

N utrition

Multicellular: consisting of many cells

Unicellular: formation/presence of many cells

Prokaryotes BEFORE NUCLEUS

→ unicellular

Prokaryotes are organisms that can be bacteria and archaea, they are single-celled organisms (unicellular).

• These cells are much more simple and smaller as they have no membrane-bound organelles. Their small size allows them to reproduce quickly and effectively.

• The size of a prokaryotic cell is typically 1-10 µm.

Structures

• Cell membrane

• Cytoplasm

• Ribosomes

• Genetic material

• Cell wall → protection

• Pili

• Flagella → cell movement/locomotion

• Capsule → layer of composed of complex carbohydrates to protect

Genetic material

Forms a large loop called the bacterial chromosome, with extra in smaller circular rings called plasmids. Since structures inside the prokaryotic cell are not surrounded by membranes, genetic material floats in the cytoplasm.

Domains

Divided into two groups:

→ Bacteria Found in many different environments

→ Archaea Found in extreme and harsh environments

Both unicellular microbial organisms.

Eukaryote TRUE NUCLEUS

→ multicellular

Organisms that fit in the domain Eukarya. They may be unicellular or multicellular, which means they can be made up of many cells.

• These cells contain a nucleus and organelles which are enclosed within a membrane.

• The size of a eukaryotic cell is typically 10-100 µm

Structures : all membrane bound

• ER

• Cell membrane

• Nucleus

• Cytoplasm

• Golgi apparatus

• Mitochondria

• Ribosomes

• Nucleolus

Microscopes

Nucleus

Function Control center, holds DNA material, brain of the cell

Structure Spherical in shape, enclosed in a double membrane. Contains chromatin that is made of DNA, which becomes organised into a number of rod shaped chromosomes.

Nucleoli

This is inside the nucleus and contains high concentrations of RNA, which is a close relative of DNA. This is important in the manufacture of ribosomes that are used in protein synthesis.

RNA: Single stranded nucleic acid that’s made of nucleotides (C,A,G,U)

Nuclear envelope

This double membrane protects genetic material by keeping cells DNA from the rest of the cell.

Mitochondria

Function Powerhouse of the cell - plays an important role in cell respiration and converting energy from glucose into energy used by cells.

Structure Mitochondria has an outer membrane and a highly folded inner membrane increases the surface area whereby the reactions occur. It has their own DNA and ribosomes.

Matrix

Viscous, gel-like space that contains a variety of enzymes, ribosomes, and mitochondrial DNA, and other molecules necessary for cellular respiration.

Granules

Composed of calcium, magnesium, and various proteins

Outer membrane

Protects organelle, only allows some substances through (small proteins). There are small particles on the outer membrane that help the flow of nutrients.

Cristae

Lines/folds that Increase the surface area for ATP production

Chloroplast

Function They contain a green pigment called chlorophyll that is vital for carrying out photosynthesis

Structure Can be seen through the light microscope

• They are surrounded by a double membrane and have internal membranes arranged in stacks. These stacks provide a large surface area where reactions (photosynthesis) occur. One of these stacks of thylakoid is called granum.

→ Liquid background of the chloroplast is called the stroma

→ Chloroplasts also have their own DNA

Ribosomes

Function where protein production occurs

Structure not enclosed by a membrane, most ribosomes are attached to membranous internal channels, called the endoplasmic reticulum, within the cell. Ribosomes contain protein and RNA

Endoplasmic reticulum

Function Transport of substances within the cells occurs through a system of channels known as the endoplasmic reticulum.

Structure A system of channels in a cell. The channel walls are formed by membranes

Smooth endoplasmic reticulum

Has no ribosomes and so it appears smooth. It is involved in the production of enzymes (lipids, fats, hormones) that assist with making various chemicals, including steroids (hormone enhancing drugs). The cells in ovaries and testes that produce sex hormones contain a lot of smooth endoplasmic reticulum.

Rough endoplasmic reticulum

Contains ribosomes on its surface that make it appear rough when viewed with a microscope. The ribosomes are the site of protein synthesis (make or create) and can either exist freely in the cytoplasm or be attached to the endoplasmic reticulum.

• Transports proteins produced by ribosomes into the golgi apparatus.

Golgi apparatus

Function Sorts, stores and dispatches the products of cell metabolism (proteins).

Structure several layers of membranes. The golgi complex packages material into membrane-bound bags or vesicles for export. These vesicles carry the material out of the cell.

Vesicle

Transport substances in and out

Vacuole

Store substances that isn't immediately needed

Cisternae

Has enzymes that modify proteins

Lysosomes

Function They release enzymes and cause cell death. Proteins, fats, and polysaccharides are no longer needed by the cell and are broken down.

• Cell’s recycling centre or waste disposal system

• Gets rid of cells infected with pathogens in a way where it can be restored and reused again.

Structure Sacs of enzymes enclosed by a membrane

Vacuole

Function Stores water and food for cells and waste (CO2)

Structure: Membrane-bound spaces that are smaller in animal cells, and larger in plant cells.

• Larger in plant cells because they require more nutrients and water -> Due to changing environments -> plants can't find nutrients on their own

Fluid Mosaic Model

Phospholipids

Forms the basic structure of the cell membrane (phospholipid bilayer) which is semi permeable.

• Phosphate head

Water attracting part of phospholipid and faces outward toward water because it is polar and hydrophilic

• Fatty acid tails

Water repelling part of the phospholipid and faces inward toward water.

Cholesterol

Maintains the membrane stability, ensuring membrane is firm but flexible

Glycoprotein

A protein with a carbohydrate chain attached – used for cell recognition, communication, and immune response. Acts like a cell ‘name tag’ that helps cells identify each other.

• Chains attach to proteins acting like name tags for all cell recognition and communication so we can recognise the substances that move in (substances that can be used) and out (waste)

Peripheral protein

Sits on the surface of the membrane. Helps with cell signalling support or anchoring of other structures.

• Signal hormones help give cell shape and support, anchoring integral proteins.

Channel protein

Acts like a pore – allows specific substances like ions (water soluble particles like sodium, potassium, and chloride) or water to pass through freely.

• More passive: opens + closes

Carrier protein

Transport substances across membranes by changing shape, after the specific molecules pass the original shape is restored. Used for larger molecules like glucose.

PLANT VS ANIMAL CELLS

MOD 3

Natural selection

1. VARIATION

Variation within the DNA of an organism

1. SELECTION PRESSURE

Occurs due to a change in abiotic or biotic factor

1. SURVIVAL OF THE FITTEST

Developing the adaptation (advantageous) allowing them to survive

1. REPRODUCTION

Pass on adaptation to their offspring

1. ISOLATION

If there is enough change/isolation over a long period of time, they become a new species, or if there isn’t they become a subspecies

Cane toads case study

They had no selection pressures acting on them in Australia

• Origin

Introduced to OLD from central and south america in 1935 to control the population of cane beetles. Due to the similar conditions of Hawaii to Australia, they were able to adapt to Australia’s conditions easily.

• Type of damage

Poisons and eats native predators, competitive, disrupts food chain

• Control

Hand collection, fences, and research

Prickly pear case study

• Origin

Introduced to QLD (had similar conditions to their native environment) from north and south america in 1788 to be used as a natural fence and dye production.

• Type of damage

Invaded grazing land, rapid spread, spiky, invaded 60 mills of acres

• Control

Introduction of cactoblastis cactorum moth, chemical herbicides, physical removal

Pressure 1: no herbivorous predators in Australia so it can:

• Avoid being consumes

• Survive to reproduce seed bearing fruit

• Increase population size

Pressure 2: Birds spread seeds in their droppings (so did the wind and floods) since they can’t digest seeds

• Increases chance of successful reproduction

• Increase population size and expands distribution

Pressure 3: Human influences (forming for dye, livestock, livestock feed)

• Germinate with help of livestock manure

• Increase population size and expand distribution

Adaptations

Structural: Physical characteristic resting to the structure of an organism

Physiological: Relating to the way an organism functions

Behavioural: How an organism relates to its environments

1. Identify adaptation

2. Describe what it allows it to do

3. Describe adaptation increase chance of survival

Diversity

Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species

• Different breeds of dog

Biological diversity which is a measure of the diversity of different species in an ecological community

• Amazon rainforests have thousands of animals, plants, insects

Ecosystem diversity which is the variation of different ecosystems found in a region

• Variety of ecosystems in australia

Microevolution : takes place over short periods of time

Macroevolution : takes place over millions of years and results in new species

Evolution: The Evidence

DNA Hybridisation

1. DISSOCIATION Double stranded Dna is split to expose the nucleotide base using heat

2. RE-ASSOCIATION Separate segments of DNA are mixed to form a hybrid molecule

3. Heat is applied again to determine how strongly the bases ave combined and hence genetic similarity between the 2 species

DNA sequencing

The exact order of nucleotide bases in the DNA of one species is compared with the sequence in a similar DNA fragment of a second species. Identifies similarities and differences.

1. A piece of dna is isolated from each organism

2. Multiple copies of each gene are made, using fluorescent dyes to distinguish the four bases in DNA

3. Computer linked equipment called a DNA SEQUENCER is used to graph and print out the entire sequences of bases, which are then compared

The more similar the order of bases in the genome, the more closely related the species are.

Comparative anatomy

Studies of the similarities and differences in the structure of organisms which is evidence of inherited characteristics from a common ancestor.

• Organisms may come from different evolutionary backgrounds but still develop similar features because they are subjected to similar selection pressures. (Analogous structures)

All mammals share the same arrangement of bones in their forelimb

• Humorous

• Radius

• Ulna

• Carpals

• Metacarpals

• Phalanges

Comparative embryology

Homologous structures can be seen in the embryo of a species but not in the adult form and this method compares the similarities and differences between embryos of different organisms.

• Organisms that shared a common ancestor will often have similar master genes (is a gene that occupies the top of a regulatory hierarchy, meaning it's responsible for directing the expression of other genes within a specific pathway). This means that the embryos will pass through similar stages of development.

Vertebrae all possess gill and tail-like structures (fish, human, chicken, pig)

Biogeography

Study of the geographical distribution of living things, the basic principle is that each plant and animal species originated only once.

• Species evolved form CA that inhabited the area

• Species often adopt similar characteristics when exposed to similar selection pressures

• If organisms geographically isolated it can only interbreed with organisms in same areas and can only pass on their characteristics to offspring in that area

• Species lives in similar conditions

Fossil dating techniques

Relative dating

Arranging fossils in chronological order

• Qualitative as it focuses on description relative to other descriptions

• Law of superposition: same fossils, each strata older than the one above

• Index fossils: the fossils that existed in limited times which make it guides

Absolute dating

Preferred technique that involves precise quantitative data

Radiometric dating from the decay of radioisotopes age of fossil is found.