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Meiosis I
Interphase - DNA doubles
Prophase I - chromatids condense to become smaller and make it easier to move; form tetrad structure (four chromatids) and perform crossing-over (exchange of genetic material); centrosomes move to opposite poles of the cell and send out spindles fibres that attach to the chromosomes, the membrane of the nucleus breaks down
Metaphase I - mitotic spindle fibres line up the tetrads in the middle of the cell, independent assortment occurs (alleles of two or more different genes get sorted into gametes independently of one another)
Anaphase I - tetrads are separated and homologous chromosomes are guided to opposite poles of the cell
Telophase I - cleavage furrow (in animal cells) forms in the middle of the cell; cytokinesis (Cyto - cytoplasm, kinesis - movement) separates cell's cytoplasm to make two unique daughter cells
Meiosis II (similar to Meiosis I)
Prophase II - same as Prophase I, no interphase and crossing over
Metaphase II - sister chromatids attach to the spindle and line up at the middle of the cell
Anaphase II - sister chromatids separate
Telophase II - same as Telophase I, but chromosomes become uncondensed (become longer again); results in 4 haploid cells
Non-disjunction disorders
Homologous chromosomes/sister chromatids don't separate during meiosis (Anaphase I/II)
This results in cells that either have too many (trisomy, meaning three) or too few gametes (monosomy, meaning one).
Down Syndrome
Commonly known as trisomy 21
This makes a person prone to heart defects, respiratory problems and leukemia. Common phenotypes include short stature, stubby fingers and toes, and a large tongue, making speech difficult.
Klinefelter's Syndrome
Two X and one Y chromosome (XXY)
A person will exhibit feminine body characteristics and people with Klinefelter syndrome are usually sterile.
Turner's Syndrome
Missing Y chromosome
People with Turner Syndrome will not mature sexually at puberty, be sterile, and have short stature. They may also have a broad neck and chest.
Germ cells are the cells that undergo meiosis to produce gametes like sperm and egg cells.
Gametes are sex cells only used for reproduction.
Hap - one
ploid - set of chromosomes
two cell divisions
four haploid cells
half
Mitosis
Prophase -
Metaphase -
Anaphase -
Telophase -
Somatic cells are any cells in the body that are not sperm or egg cells.
diploid cell
Di - two
ploid - sets of chromosomes
one cell division
two diploid cells
same
chromosomes
parent cell
Have cell wall
Autotrophs: Plantae (moss and ferns)
Heterotrophs: Fungi (yeast, mold, and mushrooms)
No cell wall
Multicellular and Heterotrophs: Animalia (insects, birds, fish and humans)
Unicellular and Autotrophs & Heterotrophs: Protista (protozoa, algae and slime moulds)
Size: 10-100 μm in diameter
Eubacteria (such as Streptococcus and E-coli) and Archaebacteria (thermophiles, acidophiles, and methanogens) are prokaryotic.
Size: 1-5μm in diameter
The collective mass of prokaryotes is 10x more than that of eukaryotes.
Thrive in environments that are too hot, cold, salty, acidic, alkaline for any eukaryote: in a nutshell, they love extreme environments.
Not all prokaryotes (such as bacteria) are harmful: most bacteria are benign or beneficial.
DNA is made up of deoxyribose sugar, phosphates and nucleotides, aka nitrogenous bases (made of adenine, thymine, guanine and cytosine).
Adenine pairs with Thymine (AT)
Guanine pairs with Cytosine (GC)
The unit of heredity, a section of DNA sequence that codes for a single protein.
The entire set of genes within an organism
Dominant: allele of a gene that hides or suppresses the expression of another allele, in heterozygous cases
Recessive: an allele that is hidden by a dominant allele; does not show in heterozygous condition, only in homozygous
Homozygous - having identical genes (one from each parent)
Heterozygous - having two different genes for a particular characteristic
True-breeding/purebred: homozygous for a trait
Hybrids: heterozygous for a trait
two genes
same position
homologous chromosomes
trait
Term that describes the variant of the allele
sex-linked
genotypes
The genetic makeup of an organism's alleles
An example of co-dominance is the ABO system of human blood types, which involves three alleles: IA, IB (co-dominant) and i (recessive).
This makes four possible phenotypes (aka blood types) possible: A, B, AB and O.
Punnett Squares
Punnett Square - a tool used to predict possible genotypic and phenotypic ratios of offspring of two individuals (when the genotype of the parental generation is known)
P generation - parental generation
F1 generation - first filial generation (offspring of P)
F2 generation - second filial generation (offspring of F1)
Monohybrid crosses
Genetic cross involving a single pair of genes (one trait)
phenotypes
Physical appearance as a result of genotypes
Such as:
Structure
Roots - absorbs water and nutrients, serves as a reservoir of leftover food, keeps the plant anchored in the ground
Stems - contain structures that transport fluids, stores nutrients, support function, home to meristems cells
Leaves - primary function: photosynthesis in order to exchange gases with the atmosphere, absorbs sunlight
Tissue Functions
Dermal - make up the outermost layer and help prevent damage and water loss
Vascular - transportation of material throughout the plant: xylem carries water and dissolved minerals, from the roots to the leaves; phloem carries up glucose made from photosynthesis combined with water from the leaves throughout the plant
Ground - storage, support, and metabolism
Meristematic - producing new cells
Adaptations
Adaptations are inherited features or characteristics that help an organism survive and reproduce in its environment. (long-term response)
Tropism
Tropism is a plant's response to an environmental stimulus. It can cause a plant to grow toward or away from a stimulus. (short-term response)
Systems
Digestive
Mouth - teeth chew food, tongue positions and taste food
Pharynx - passageway for food and air, participates in swallowing
Esophagus - moves food from the pharynx to the stomach
Stomach - stores and mixes food, begins chemical digestion of protein by enzymes and acid, regulates delivery to the small intestine
Large Intestine - absorbs nutrients, stores waste material
Small Intestine - digest proteins, fats and carbohydrates, absorbs most of the nutrients, secretes digestive hormones and enzymes
Rectum - passageway for feces
Anus - expels undigested material
Salivary glands - saliva moistens food, amylase digests starch
Liver - produces bile, performs various functions associated with processing and storing nutrients
Gall bladder - stores and concentrates bile
Pancreas - secretes digestive enzymes into small intestine
Macromolecules
Carbohydrates: glucose monomer; the primary source of energy & structure for chitin and cellulose
Proteins: amino acids monomers; structural support of hair and nails, controls the movement of material going in/out of cells
Lipids: hydrocarbon monomers; long-term energy storage & main structural components of cell membranes
Nucleic acid: polymer of similar monomers called nucleotides; composite molecules made up of sugar, phosphate and nitrogenous base
Circulatory
Blood - delivers oxygen, nutrients and hormones to cells
Blood vessels
Respiratory
Nasal cavity - where hairs and mucus trap large inhaled particles
Pharynx - aka the throat, it serves both the respiratory and digestive systems by receiving air from the nasal cavity, and air, food and water from the oral cavity
Larynx - acts as a passageway for air between the pharynx above and the trachea below
Trachea - aka windpipe, lined with mucus-producing cells which traps airborne particles and microorganisms
Bronchi - they branch off of the trachea and carry air directly into the left and right lungs
Bronchioles - smaller airways than the bronchi, they terminate in grape-like clusters known as alveoli
Alveoli - surrounded by a network of thin-walled capillaries, and they perform gas exchange by diffusion, which takes place between the capillaries and a vile alveoli walls (specifically O2 and CO2)
Any change in the heritable traits within a population across generations is considered evolution.
Evidence
The study of evolutionary relationships between and among species.
Scientists can compare living species with extinct organisms through phylogenetic analysis.
Root = ancestral lineage
Tips of branches = descendants
Therefore root --> tips = moving forward in time
We also talk about LUCA, last universial common/cellular ancestor (not the first living organism but the farthest we can trace back to).
clades
A clade is a grouping that includes a common ancestor and all living/extinct descendants of that ancestor.
A population of individuals that are able to breed freely under natural conditions and produce viable offspring
Structural diversity
Species diversity
The science of identifying and classifying all organisms. Named after Carl Linnaeus who formalized this system.
Organisms are classified using dichotomous keys and binomial nomenclature.
Taxa = arrangement, nomos = law
In order from least specific to most specific, the taxa (ranks) are:
Humans can be classified this way:
Protista
Binomial nomenclature
Format: Genus species
Language: Latin (and sometimes Greek)
