Biology Notes

Cells

Organelles:
Organelles: Structures that enable the cell to live, grow, and reproduce
Ribosome: Helps in the systehensize of proteins and its where proteins are made
Lysosome: Removes waste from the cell. They also prevent the entry of unknown particles, digest food & unwanted cell parts that have no function.
Vacuole; Is the largest organelles in a plant, it stores water, food, & waste for them.
Platid: Present in only plants; plastids store food for the plant. Sometimes, they also have pigments to help the chloroplasts absorb sunlight
Cell Wall: Gives the shape of a cell, protects it from natural disasters, prevents animals from eating the plant, and protects all the organelles inside. The cell wall is made up of hemicellulose and cellulose. They both are organic compounds made up of carbon, hydrogen, and oxygen. The formula is c6h10o5
Clorplasts: Consist of pigments such as chlorophyll a, Chlorophyll b, Cratitonoids, Xanthophyll which entraps the sunlight and helps in the photosynthesis process. Chlorophyll A absorbs the most sunlight. The main part of chloroplasts include the stroma(the place where dark reaction occurs , thylakoids (the sight where photosystem 1 takes place), lamella (connects all the parts together) granum (stack of thylakoid), ribosomes (helps in the synthesis of proteins , grain starch (storage form of glucose present in only plants), intercellular space (free space), and double membrane structure (two membranes) Photosynthesis 1 is a light dependent reaction, photosynthesis 2 is the same thing as photosynthesis 1 but it’s cyclic in nature and a dark reaction requires no light for the reaction. Stomata helps in the exchange of gases in the plant. The formula of glucose is C6H12O6. In the fall, cells in the chloroplast form a wall blocking the water supply causing the leaves to fall ot, Chlorphyll A and B cannot withstand te excessively cold temperatures which rresult in the colors changing from a wide variety of pigments invlving red, orange, or yellow
Membrane: Consists of a nonpolar tail and polar head. The polar head is attracted to water, but the nonpolar tail repels water. Plasma membrane is often known as the lipid bilayer because it is made up of lipids. It is selectively permeable in nature which means that it only lets in selective things in the cell. Many things will try to enter the cell but the lipe bilayer (set of non polar tails) will prevent them from getting inside. As a result, invading microorganisms will try to enter from proteins which act like a gateway and are chemical receptors for communication. The plasma membrane maintains shape & and size of the cell, protects internal contents of the cell, and regulates entry. The three types of protein in the lipid bilayer are outer protein, inner protein, and embed protein. The cell membrane is made up of lipoprotein which is what the lipid bilayer is made of
Endoplasmic reticulum: it provides the surface area to the ribosome to help in protein synthesis. They also are of two types which includes smooth (SER) and Rough (RER) endoplasmic reticulum. SER helps in transportation of RNA, and SER has small ribosome beads on their surface which helps in protein synthesis
Nucleus: Contains the genetic material of the cell and
Cytoplasm: Is the jelly-like substance in the cell. All organelles float in this semi liquid.
Golgi Complex; Is the shipping part of the cell. It ships stuff out of the cell and it processes packages almost like UPS. It does the packaging of the protein needed for the cell
Chromosomes: thread like structures (almost like a butterfly) located inside the nucleus of plant and animal cells. It’s composed of DNA & protein, and it has two identical chromatids. (arms) If the chromatids are attached to the same centromere (a small ball like structure in the middle of the chromosome) they are considered sister chromatids, but if they are attached to different centromeres they are often known as non-sister chromatids. DNA is located in the chromatids. Centromeres attach to the spindle fiber released by the centrosomes (located near the nucleus) during cell division which is a major part of the Telophase process. Telomeres are present at the edge of chromosomes which have satellite DNA. Satellite DNA is the region which has repeated sequences of DNA.
Homologous and Nonhomologous Chromosomes: There are two types of chromosomes which include homologous and nonhomologous. Homologous chromosomes are the one which are having the same genes at the same location (in the same sequence like their parents, so they look exactly like their parents) Nonhomologous chromosomes are the pair of chromatids not consisting of the same sequence. As a result, they will look different than their parents.
Mithrochronida: Power center of the cell, and provides power to the entire cell by synthesizing the energy currency which is ATP(AdenosineTriPhosphate) with the help of ETC (Electron Transport Chain)
Cell Cycle:
The cell cycle consists of two main steps which consists of the M phase and the Interphase. They both have further sub steps which help the cell clone itself.
Interphase: The interphase is the preparatory (preparation) phase which consists of three sub phases such as, G1 Phase, S (Synthesis) Phase, and G2 Phase. In the G1 phase the cell collects all the raw materials (enzymes, minerals, ions, and proteins) in order to prepare for replication. It’s also the time when the cell enlarges and is metabolically active.The S Phase is the most important part of the cell cycle because it’s where replication (when DNA forms its own replica) In the G2 phase, protein synthesis (transprication) takes place with the help of Ribosomes.
M Face : The M face is divided into 4 stages which includes Prophase, Metaphase, Anaphase, and Telophase. In prophase, condensation of chromosomes (they will form the butterfly shape) take place which means we can observe the chromatid structure during this phase, but you can’t see any organelles. In the Metaphase, all the chromosomes will align at the metaplate (equator) of the cell with the help of the spindle fiber. Kinetochores attach to the spindle fibers which help align all the chromosomes in the middle in order for the cell to divide. In the Anaphase, the centromere splits and chromatids separate to move towards the opposite pole. In the TeloPhase, the chromosomes cluster at the opposite pole and the nuclear envelope will enclose the chromosome cluster. Then, all the organelles will reform again and we can see them under a microscope. The cytoplasm will also divide can you can see the jelly-like substance moving. Slowly, the cell starts to split into two daughter cells. Now the cell has been formed into 2 cells which will look exactly like the same because they have the same genetic material.
Karyokinesis: The nucleus membrane divides into 2 nucleases
Cytokinesis: The cytoplasm divides into 2 cells
Meiosis: a type of cell division also considered as reductional division which means the number of chromosomes in parent cells reduced by half and produce four gametes (the reproductive cells of males and female. For example, an egg is for a female and sperm is for male. If the gametes fuse with each other they will fertilize and form a new human) Male gamete has 23 chromosomes and so does the female. Together , they will form a complete DNA structure.
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Cell Discovery:
Robert hooke discovered the cell in 1665
He had observed a slice of cork (bark) under a microscope where he noticed a bunch of small compartments, cells
Robert Hook was the first person to use the word cell which is latin for small compartments
The smallest cell discovered is mycoplasma which is 1/1000 of a millimeter or 1. Micrometer
The largest cell discovered is an ostrich egg which is 18 inches in diameter
Cellular Organization:
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What do they do:
Are the basic units of life
Have different functions that makes a complete organisms
Cellular Level Of Organization: If many cells come together they form a tissue which are specialized cells that perform separate functions. The tissues then combine together to form an organ which performs a special function. The organs later combine to form an organ system. Organ systems combine together to form a complete living organism

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Types of organisms:
Viviparous: Animals that give birth to young ones
Oviparous: Animals that lay eggs
Ovum: eggs
MultiCellular: Organisms that are made up of more than one type of cell.
Unicellular: Organisms that are made up of only one type of cell. Some examples include Amoeba and Paramecium. Amoeba has lytic enzymes which help break down its food (other living microbes) into small fragments. Amoeba makes fase feet to move and capture its prey. Otherwise, this organ has no specific shape.
Smaller Organism: Not as complex body systems and cells do many functions
Higher Organisms: Complex body systems
Asexual Organisms: Organisms that give birth with only 1 parent and their offsprings look exactly like them (Clones).
Pseudopodia: an organism that changes shape to make false feet
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How many cells?
All organs have a variety of cells that have different cell numbers, shape, and size
There are trillions of cells in humans
The size of cells ranges from a millionth of a meter to a couple millimeters but most of them are extremely small
The largest cell is the egg of an ostrich, and the smallest is found in bacteria
How do we see cells
We use a magnifying device to see cells
We use stains to help differentiate and visualize cells
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Different Types of cells
Prokaryotic Cells: Prokaryotic Cells have no membrane bound organelles and have circular DNA. For example, bacteria and viruses are prokaryotic. Some parts of prokaryotic cells include Cilia and Flagella. Flagella helps with the movement of the cell, and Cilia is responsible for transduction and a little bit of movement.
Eukaryotic Cells: These cells consist of membrane bound organelles. For instance all animals and plants are made up for eukaryotic cells.
Red Blood Cells: RBC don’t have a nucleus or mitochondria because they need space to collect oxygen and nutrients in order to deliver it to every cell in our body. The heme groups cause the cells to be red which also results in the blood to be red when oxygenated. In addition, a red blood cell
White Blood Cells: Similar to amoeba they can change shape and engulf their prey (viruses) The only difference is that white blood cells are a single cell but ameba is a complete organism
Nerve cells: Consist of dendrites, axons, and cell bodies
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Membrane Transport
Hometstatis: the ability to sustain a constant condition at a particular time in the cell
The plasma membrane is often known as the lipid bilayer and it consists of two parts such as phosphates and lipids which together are known as phospholipids
Phosphate is the polar reason of the membrane, (hydrophilic; water loving) The lipid is the nonpolar reason of the membrane (hydrophobic; water repelling)
Membrane Transport: Cells do transportation either by active (use of ATP or energy) or passive mode (no use of ATP or energy)
Active Transport: When cells utilize the energy for the transportation of particles across the membrane
Passive Transport: When there is no utilization of energy and particles can cross the membrane without any energy

Membrane Proteins Functions
Ion Channels: allows flow of ions in and out the cell
Carrier Proteins: This protein facilitates the movement of particles (any molecule that wants to come in and out the cell)
Receptor Proteins: These receptors present on the proteins helps in cell communication and the proteins are very specific towards their receptor
Linker Protein: These proteins help in cell anchoring either by binding the different proteins of different cells or through their filaments. This protein helps form tissues as cells must group together in order to form a tissue
GlycoProteins: GlycoProteins are the cell identity markers. They help the immune system function properly by monitoring antigen and antibody interaction.
Antigens: Antigens are foreign particles that can activate our immune system
GlycoLipids: These are also a type of cell identity marker. This type of lipid protein also provides stability to the cell membrane. Sometimes it also facilitates the movement of foreign particles
Cell Energy
Cells need ATP (AdenosineTriPhosphate) in order to survive. The mitochondria synthesizes bone energy in order to make ETP which will power the entire cell.
When you remove 1 phosphate from ATP it will form ADP (AdenosineDiPhosphate)
Solution: mixture of solute and solvent where solute will be present in a lower amount and solvent will be present in a larger amount. For example, mixture of salt and water where salt will act like a solute and water will be the solvent
Diffusion: a process which takes place in between gases. The 5 factors of diffusion is a change in the gradient, change in temperature, distance, surface area.In facilitated diffusion particles must hitch a ride with a particle that is allowed to go in the cell. In simple diffusion particles are permeable in the cell
Different types of diffusion includes channel meditating which involves the concentration of the gradient to a channel protein
Osmosis: a process in which molecules of solvents pass through the semi-permeable cell membrane from less concentrated solution to more concentrated solution.
Solution Tonicity: measure of a solution’s ability to change the volume of the cells by changing the water content. In Isotonic the amount of water inside and outside of the cell is the same, so the cell’s size will stay the same. In hypotonic there's more water and less solutes. As a result, the cell will get large. In hypertonic there is less water and more solutes, so the cell will shrink as there is less water. In cytolysis there is a chance that the cell might burst from all the extra water, and plasmolysis is when the size of the cell shrinks down.
The cell gets energy from the hydrolysis of the ATP. The cell utilizes the ATP using the equation, ATP=ADP+PI+Energy
Membrane Transport in Bulk: use of membrane bound vesicles to bring substances in and expel. In Endocytosis, the cell brings in materials to the cell, Phagocytosis, the cell breaks in solids, Pinocytosis, the cell brings in non specific fluids, Receptor Meditats, the cell brings in specific particles, and Exocytosis, the releasing of materials from the cell
DNA
Has genes in the form of codones. Three nitrogenous bases form a codon. The nitrogenous bases are the genes themself and there is nothing inside them
Cells produce DNA which produces RNA and RNA turns into proteins. This process is often known as central dogma. Transcription is when DNA turns into RNA, and translation is when RNA turns into Proteins When DNA makes a copy of itself, it’s known as replication.
Watson and Crick discovered DNA in 1953
The component of DNA is Nucleotide which is the monomer unit (the same unit that keeps repeating) .
DNA: deoxyribonucleic acid located in the nucleus of the cell which is double helix in structure and contains all the genetic traits in the form of genes, transferred genes from parents to their offspring (children)
Nucleotide: It’s made of three components which include pentose sugars, nitrogenous base, and phosphate group. It’s the monomer unit of DNA. Pentose Sugars, and the phosphate group are the backbone of the DNA. They support the small rungs in the twisted ladder which are often known as the nitrogenous base. The Nitrogenous bases are of two types; purine and pyrimidine. Purine is further of two types which includes adenine and guanine. Pyrimidine also consists of two parts which include Cytosine and Thymine. Adenine and Thymine will always bond with each other using a double hydrogen bond. Cytosine and guanine will always bond with each other using a triple hydrogen bond. The chargaff's rule is the purine will always bind with pyrimidine. The phosphate group and the pentose sugar link with each other to form a phosphodiester Bond , which is strong.
Codon: Codons are present in triplet forms of nitrogenous bases. A sequence of three nucleotides which together form a unit of genetic code in DNA and RNA molecules. In other words, three nucleotides form 1 gene which is the coding for amino acid.
Protein: Proteins are made up of amino acids which joi through peptide linkage or bond. They are large biomolecules composed of 1 or more long chains of amino acids, and are an essential part of living organisms. Proteins are present in all living organisms. According to the basic structure of amino acids, the central carbon atom (chiral carbon) is linked with 4 different groups, such as hydrogen, amino group, carboxyl group, and variable group (R) Chiral carbon is what the four groups are attached to center carbon. There are twenty basic amino acids
Twenty Amino acids: There are twenty amino acids which are further categorized into essential amino acids and non essential amino acids. Essential amino acids are those that we have to consume through our diet because our cell cannot synthesize them. can make non essential amino acids.
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Molecular Genetics

Genetics
Molecular Genetics is the sub-branch of biology where we study genes, DNA, and their structure and functions.
We use molecular genetic concepts in recombinant DNA technology, gene therapy for the manipulation of genes
Discovery
Geroge Mandel is known to be the father of genetics. He was born on 1822 and died on 1884. He was an austrain monk
Mendelin Genetics: all living organisms reproduce. It results in offspring of the same kind, the offspring may not totally resemble the parents
Important terms
Homozygous Chromosome: a cell is said to be homozygous when identical alleles of genes are present on both the chromatids of chromosomes
Heterologous Chromosome : a cell is said to be heterozygous when its cells contains two different alleles of genes
Genetics: the branch of life science that deals with • Genetics is the branch of life science that
deals with the study of heredity and variation.
Heredity is the transmission of characters from parents to their offsprings.
Variation is the difference among the offsprings and with their parents.
Heriditary variations: These are genetical and inheritable.
Environmental variation: These are aquaired and non heritable.
Gametes: the parts of male and female used to fertelize. For example, eggs and sperm.
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George Mandel:
1822- 1884
Austrian monk
Hybridization Experiment with pea plants.
Published his results
“Translation of the characters” in the natural history of society of brunn
Mendel (1822-1884) was born in to the family of a poor peasant in Moravia, Austria.
He suspended his school education due to poverty in the family.
In 1843 he joined a church as a monk.
In 1847 he became the head of the monastery at Brunn, Austria (now called Bruno in Czechoslavakia).
In 1851 he went to University of Vienna to study natural history and mathematics, for two years. After his return he worked as a
teacher in natural history and mathematics between 1856 and 1865.

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Body systems

Nervous System
Contain sensory receptors called stimulus that pick up signals from the environment. Different types of stimuli include
Mechanical: involved with touch and hearing
Chemical: involved with smell and taste
Electromagentic: involved with sight
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