Biology Evolution and Cell Specialisation

Chapters: Theme 1: A3.1, A4.1, B4.1, D4.1 Theme 2: A2.2, B2.1, B2.2, B2.3

Karyotype

Picture of all chromosomes in a cell.

Structure of pair of chromosomes

Centromere and dark bonds tightly packed and rich with A and T.

SNP (single nucleotide polymorphism)

Differences that can be found often in a non-coding region. SNP can be used for finding genetical diseases.

Evolution

Cumulative change of the characteristics of a population passed on genetically from one to another. Explains how species evolve.

Epigenetics

environmental factors and other factors that can affect on the genetics of the offspring.

Evidence for Evolution

Genome: total amount of DNA in an individual

Protenome: proteins in an individual

Homologus structures: same structure of traits, different functions. eg. pentadactyl limbs

Analogus structure: similar structure of traits, different functions. eg. Wings of birds and butterflies

Vestigal organs: organs that are no more useful but we still have them

Convergent and divergent evolution

Selective breeding: process in which humans choose animals with desirable characteristics to breed.

Convergent evolution

Similar traits in unrelated species. Explained by analogous structure.

Divergent evolution

Different traits from a shared ancestor. Explained by homologous structures.

Adaptive radiation

Different functions but same kind of bones placed in similar position in the build. eg. vestigial organs

Speciation

splitting pre-existing species to form new species, by letting natural selection act differently on both populations.

Ch. B4.1 Adaptattion to the environment

Biome

Group of ecosystems with similar abiotic factors.

Habitat

Environment that provides the basic requirements for an individual to survive.

Ecosystem

Defined area where species live and interact with the biotic and abiotic factors of that area.

Niche

The unique role of a specie in an ecosystem.

Range of tolerance

Range of the specific abiotic factor where species survive.

Examples of biomes

Tropical forest

Taiga

Tundra

Hot desert

Grassland

Temperate decidious forest

D4.1 Natural selection

Mutation

A random change of a coding sequence of a gene. Can be caused by radiation and happens during the cell division when DNA is being copied.

Meiosis

Cell division for gamets (diploid cells). A single secs cell goes through two division phases to produce four daughter cells:

1. DNA gets copied in the cells and divides once which seperates the matched chromosome pairs. In this phase, two cells are created with half the normal number of chromosomes.

2. The two new cells divide and copy the DNA again. This results in total of four new cells, each one of them containing unique single set of chromosomes.

Crossing-over occurs and cells are not identical because of crossing over.

Natural selection

Evolutionary process where organisms with better adapted traits to their environment are more likely to survive and reproduce.

Carrying capacity

The amount of individuals that survive in the ecosystem with the amount of resources and limitations present.

C2.2 Cell structure

Common cell structure:

Plasma membrane: barrier that controls what goes in and out of the cytoplasm.

Cytoplasma: hydrophilic environment where metabolism occurs.

Nucleus: contains the cell’s DNA, not all cells have nucleus.

Homeostasis

Keeping a constant internal environment.

Prokaryotic cell structure:

Small

Cell wall, made of peptidoglucan (peptide + polysaccaride)

No nucleus, DNA swims around in the cytoplasm

Lacks membrane bound organelles

70s ribosomes

Organelles

Structure inside the cell within its own cell membrane. Has a specific function, is a dscrete subunit in the cell.

Eukaryotic cell

Contains:

Nucleus: which has double layered membrane with pores and contains the cell’s DNA which is packed in chromosomes.

Mitochondria: the place where cell respiration occurs. It has double-folded membrane, cristae and liquid matrix and produces ATP.

Ribosomes: non- membrane bound organelles, made of proteins and RNA. Carry out protein synthesis. Size 80s.

Golgi apparatus: packs up the proteins and molecules before they are sent out of the cell. Made of flattened membrane sacks and vesicles.

Endoplasmatic reticilum: chanels connected to the membrane. There are two types: rER and sER. rER are the rough chanels which have ribosomes attached and sER are the soft ones that swim around.

Lysosomes: contain enzymes that disolve the substances that enter the cell.

Centrioles: stay close to the nucleus and help with cell division.

Cytoskeleton: network of protein fibers.

Cystic fibrosis

Malfunction of a chanel located in the cell membrane that transports chloride ions. This prevents proper movement of salt and water which leads to mucus build up in the lungs and digestive track.

Alzheimer’s and Parkinson’s

Phospho-lipids

Building blocks of the plasma membrane

Peripheal proteins

Get attached on the membrane and help the imune system identify its cells and not attack them.

Aquaporins

Integral proteins that transport water

Diffusion

Movement from high to low cocentration of a substance, eg. water

Conentration gradient

The different concentration in different areas

Active transport

Process through which substances are being tranported in the cell by using ATP. Goes against the concentration gradient.

Osmosis

Movement of the water molecules across the membrane.

Chloresterol

Stabilizes the membrane by influencing the fluidity of the membrane. Sits between the phospho-lipids of the membrane to keep it rigid. Too much is harmful.

Autoimmune disease

The immune system doesn’t recognise the type of cells and starts attacking the healthy cells.

Enzymes

Speed up the chemical reactions. Require specific pH. By having different compartments, i.e. membrane bound organelles, enzymes can work very well at the adapted pH inside the organelles. If pH is mixed enzymes would fail to work