Biology H Study Guide

Homeostasis

Definition - The ability to ^^maintain a stable internal environment^^ despite changes in external conditions through negative and positive feedback(equal).

Negative feedback vs Positive feedback

• ==Negative feedback loop:== Allows organisms to keep a ^^small range of parameters^^. An example of this may be that when there’s a ^^change in our internal temperatures^^ our bodies react in a certain way to return our body temperature to the set point that it should be.
• %%Positive feedback loop:%% Its ^^stimulus is in the same direction as the response.^^ An example of this is ^^fruit ripening,^^ when the fruit ripens they produce a hormone called ^^Ethylene^^ which travels in the form of gas. This hormone can be picked up by unripened fruit in close proximity to the ripened fruit, like how a ripe apple can allow other apples close to them to mature and produce more Ethylene which causes more fruits to ripen this repeats until there are no more unripened apples left. This is why apples on trees seem to ripen at the same time.

How does one cool down and heat up?

• Someone can cool their body by ^^sweating,^^ the sweat will ^^slowly evaporate from their bodies^^ cooling down their skin, the blood will rise towards the skin surface, and ^^through convection^^, we lose more of that heat.
• Someone can heat up their body by ^^shivering, creating goosebumps, and vasoconstriction^^. When we shiver, we are moving rapidly but still stay in one place, by creating goosebumps ^^our skin is tightening up like a coat^^, and vasoconstriction ^^pulls the blood towards the body to heat up^^ the blood and having less convection.

What is a Neuron/what does it do? What system is it a part of?

^^Neurons are information messengers.^^ They use ^^electrical signals and chemical impulses to transmit information between different areas of the brain^^ and between the brain. It’s part of the ^^Nervous system.^^

What is a pathogen?

It’s an organism ^^causing the disease to its host,^^ with the severity of disease symptoms referred to as ^^virulence. e.g bacteria, infections, etc.^^

Fight or flight involves what system?

^^The sympathetic nervous system^^ is a network of nerves that help your body activate its “fight or flight” response. The system’s activity increases the more you are ^^stressed, in danger, or physically active.^^

• The Nervous system ^^controls and coordinates all body activities through^^ ^^electric impulses/messages between the brain, spinal cord, and nerves.^^

Hormones are part of what system?

The ^^endocrine system^^ is made up of glands that make hormones. Hormones ^^carry information and instructions from one set of cells to another.^^ The endocrine system ^^influences almost every cell, organ, and function in our bodies.^^

Immune system: are fevers good or bad? Why do we get them?

• ^^Fevers are good^^. They are a protective mechanism and ^^a sign that the immune system is working.^^
• We get them because our bodies are ^^trying to kill the virus/bacteria that caused infections^^ that are inside our bodies. Since these bacterias and viruses ^^survive well in our normal body temperature if we raise it they’ll die easier.^^

What is the connection between glucose and insulin?

it’s a ^^negative feedback loop^^ when they both help the body remain a ^^stable blood sugar level^^. When blood glucose levels are ^^high, insulin will be secreted^^ by the pancreas, triggering cells in your body to convert that extra glucose into glycogen and store that glycogen in your liver. When blood sugar levels are ^^low, glucose is provided instead of insulin^^, allowing your blood sugar levels to up.

Prokaryotes vs Eukaryotes

• %%Prokaryotes%% - ^^Non-bound organelles^^ that ^^don’t have a nucleus^^
• ==Eukaryotes== - ^^Has bound organelles, a nucleus/membrane,^^ and can be both ^^plant and animal cells.^^

Cell organelles: Ribosome, Mitochondria, vacuole, cell membrane, cell nucleus

• {{Cell organelles: ^^Subcellular structures^^ that have ^^1 or more specific jobs to perform in the cell^^{{
• Ribosome: ^^Creates protein through synthesis^^
• {{Mitochondria: ^^Supply power^^{{
• Vacuole: ^^Helps sequester waste^^
• {{Cell membrane: ^^Regulate the transportation of materials entering/exiting the cell^^{{
• Cell nucleus: Stores ^^cells heredity material/DNA^^

Relationship between cell cycle and cancer

Cancer cells ^^will not stop dividing due to a mutation of the DNA^^ that produces a ^^protein in the cell cycle.^^

Cell specialization/Cell differentiation

• ==Cell specialization== - The cell ^^specializes from ‘generic’ cells into a cell that performs a unique function^^
• %%Cell differentiation%% - ^^Cells are all different^^

Mitosis

Definition - A ^^type of cellular division that splits through 4 phases^^ and creates 2 identical daughter cells.

• Why it happens - It happens because it ^^allows growth and it replaces the old worn-out cells.^^
• End result - The end result is ^^2 identical daughter cells.^^
• Phases - ^^Interphase, prophase, metaphase, anaphase, and telophase^^

Meiosis

Definition - A type of ^^cell division in sexually reproducing organisms^^ that ^^reduces the number of chromosomes in parent cells in half and produces 4 gametes^^ (daughter) cells.

DNA

Definition - ^^Deoxyribonucleic Acid^^ that contains phosphate, deoxyribose, and a base. It’s a ^^long-chained molecule that contains the genetic blueprint for building and maintaining a living organism.^^

Nucleotide structure

A nucleotide structure contains ^^phosphate, deoxyribose (sugar), and a base^^. The base can be 1 of 4.

Base pairing rules

DNA:

RNA:

What is meant by DNA as a universal code?

All known living organisms use the same genetic code, ^^every organism uses DNA to store genetic information.^^

Replication

It’s the process by which a double-stranded ^^DNA molecule is copied during cell division to produce 2 identical DNA molecules.^^

Transcription

The process by which the ^^information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA)^^

Translation

The process by which a c^^ell makes proteins using the genetic information carried in mRNA^^

Reading frame/codons

How the ^^nucleotides in a nucleic acid molecule are grouped into codons^^, with each codon containing ^^3 nucleotides.^^

How DNA goes to RNA to Protein

DNA - Transcription - RNA - Translation - Protein

Types of Mutations

• {{Point Mutation - ^^One base pair is different^^{{
• ]]Frameshift Mutation - ^^Addition/subtraction^^ of base pair]]
• {{Missense - ^^Wrong amino acid is put in^^{{
• ]]Nonsense - ^^“Stop” codon is inserted (UAA, UAG, UGA)^^]]
• {{Silent - ^^Change didn’t affect amino acid^^{{

Relationship between DNA, chromosomes, and genes

• ^^Chromosomes carry DNA in cells^^
• ^^DNA is responsible for building and maintaining the human structure^^
• ^^Genes are segments of your DNA^^; give you physical characteristics

How many chromosomes do normal humans have? Do all organisms have the same number of chromosomes?

• Humans have ^^23 pairs of chromosomes. 46 in total.^^
• Not all organisms have the same amount of chromosomes. ^^Each organism has a set number of chromosomes^^. e.g. Fruit flies have 4 pairs of chromosomes 8 in total.

Dominant vs Recessive

When in a heterozygous pair of alleles the ^^dominant gene will be expressed over the recessive one.^^

Homozygous vs Heterozygous

• Homozygous: When both ^^alleles are the same^^ (YY, yy)
• Heterozygous: When the ^^two alleles are different^^ in dominant and recessive terms (Yy)

Pedigrees

^^A diagram of family history^^ that uses standardized symbols, shows the relationship between family members and indicates ^^which individuals have certain genetic traits and diseases within the family.^^

Punnett squares

A punnet square is a ^^square diagram that’s used to predict genotypes^^ of a particular cross/breeding ^^between 2 parent organisms. Named after Reginald C. Punnett.^^

Phenotype/Genotype

• %%Phenotype:%% The ^^physical or observable^^ characteristics of an organism that can be influenced by the environment and genotype
• ==Genotype:== The ^^genetic^^ ^^constitution^^ (“appearance”) of an organism

Natural Selection

• The ^^process through which a population of living organisms adapts and change^^
• Helps their ^^survival^^
• ^^Adapt to their surroundings/environment.^^