Biology Unit 3 Flashcards
Cellular Respiration
C6H12O6 + O2 —–> Co2 + H20 + Energy Intermediate
Cellular Respiration is high in areas with mitochondria. Liver, Muscles and Nerves.
Glucose is being oxidized to Co2. Oxygen is being reduced to water.
Nerves can only use glucose as its energy source so it is important that we have enough glucose to break down.
Cellular Respiration Energy
27-29 ATP + Heat (Heat is used for temperature regulation)
Cellular Respiration is a Exergonic Reaction with a Delta G of -686kal/mol. (Opposite of Photosynthesis G= 685 kal/mol)
How is glucose broken down?
Glucose is broken down in many steps using many different enzymes/redox/coenzymes in order to achieve full amount of ATP
NAD
You only need a small amount of NAD because you can reuse them. NAD+ is reduced to NADH and NADH is oxidized to NAD.
In its reduced state it is holding energy
Glucose Breakdown
Glucose going to be broken down (Glycolysis) in both eukaryotes and prokaryotes.
Glycolysis: Simple Overview
Process that happens in the cytoplasm of all cells. It breaks down Glucose into 2 pyruvate and generates ATP in the process
Transition Reaction Process: Simple Overview
Both pyruvates are going to be oxidized. Energy is going to be stored in NADPH and 2 carbons are released as CO2.
Citric Acid Cycle (Krebs Cycle): Simple Overview
Happen in the mitochondrial matrix.
Electron energy is stored as NADH+H and FADH2.
4 carbons are released as Co2
Mitochondrial Diseases
Mutations in mitochondrial DNA can affect the cells energy demand. If this energy demand is not met it can ultimately be fatal. This effects the brain, muscles and nerves
Oxidative Phosphorylation
Extracts energy from NADH+H and FADH2. Generates 23-25 ATP using the ETC and ATP synthase
Glycolysis
Nerves can only use glucose as an energy source so it is very important.
Has a energy investment phase and a energy harvesting phase.
Glucose phosphorylation requires an enzyme at each step
Energy Investment
Glucose needs to be activated by 2 ATP. The phosphates from ATP get transferred to Glucose to phosphorylate it and ATP turns to ADP. Glucose phosphorylated is fructose diphosphate. In the state glucose is now irreversible since it is changed.
Fructose Diphosphate (6 carbons) is split into 2 G3Ps at the cleavages. G3P is a 3 carbon molecule.
G3P
Is a 3 carbon molecule with a Aldehyde, Alcohol and Phosphate group.
Aldehyde= H-C=O
Alcohol= C-OH
Energy Harvesting
G3P is changed to pyruvate. Since this is a oxidation (G3P sends 2 electrons and protons to NAD), 2NAD is converted to 2NADH+H. 2ADP are changed to 2ATP by a substrate level phosphorylation (G3P phosphate goes on the ADP).
Feedback Inhibition with Glycolysis
Since ATP is produced, if there is enough ATP present it will bind to Phosphofructokinase (PFK) and inhibits the rest of glycolysis. Well ATP levels fall the inhibition is going to be removed (not binding).
Oxygen and Glycolysis
If oxygen is available then the pyruvates will continue to go to the Krebs Cycle, if there is no oxygen then they run anaerobically.
Substrate Level Phosphorylation
Phosphate from substrate is attached to ADP to make ATP
Glycolysis Formula
C6H12O6 + 4 ADP + 2 ATP+ 2 NAD + 4P ——> 2 Pyruvate + 4 ATP + 2 NADH + 2 ADP
Transition Reaction
Pyruvate enter mitochondrial matrix through Hydrogen / Pyruvate Symporter (Co transport, secondary transport and symport).
Pyruvate gets decarboxylated and turns into a acetyl group (2 carbons). Co enzyme A is added to the acetyl group. = Oxidations
So, NAD+ —> NADH (times 2)
Pyruvate + coA —-> acetylcoA + co2 (times 2)
Co2 gets transported out of mitochondria and goes out the lungs
Krebs (Citric Acid) Cycle
Occurs in the mitochondrial matrix.
Acetyl CoA splits and CoA is transported back to the transition reaction. Acetyl combines to oxaloacetate (c4) to make citrate (c6). Citrate is decarboxylated to c5 while NAD+ is reduced to NADH. Co2 is released. c5 is decarboxylated to c4 and NAD is reduced to NADH. Co2 is released and ADP gets phosphorylated by a substrate phosphorylation to ATP. c4 molecule is called succinate. Succinate gets oxidized to fumarate and FAD gets reduced to FADH2. Fumarate then gets oxidized to make oxaloacetate.
Competitive Inhibition: Oxaloacetate and succinate act in competitive inhibition on succinate dehydrogenase. If there is a lot of oxaloacetate then it will bind to succinate dehydrogenate and slow down the Krebs cycle. If there is more succinate then it will bind and the Krebs cycle will continue to go on.
2 Oxaloacetate + 2 Acetyl CoA + 6 NAD + 2ADP + 2FAD —-> 2 Oxaloacetate + 2 CoA + 6 NADH + 2ATP + 2FADH +4Co2
Does the Krebs cycle use oxygen?
No but it has to be present for it to run
Oxidative Phosphorylation
The process in which ATP is formed using energy from NADH and FADH2 to oxygen by a series of electron carriers
Location of Oxidative Phosphorylation
In Eukaryotes: The cristae of the mitochondria
In Prokaryotes: The plasma membrane
A series of carrier molecules
Pass energy rich electrons across an array of proteins and cytochromes
Cytochromes
Are respiratory molecules with complex carbon rings with metal atoms in the center
Electron Transport System
The fate of hydrogens: Hydrogens from NADH+H gets oxidized to NAD and their electrons flow down the ETC
Energy Yield per Glucose Molecule
In the cytoplasm: Glycolysis is going to generate 2 ATP and 2 NADs.
In the Matrix: Transition reaction produces: Co2 and 2 NAD
Krebs: Generates 6 NADH, 2 ATP, 4CO2 and 2 FADH
Substrate Level Phosphorylation (before ECT) makes 4 ATP
ETC generates around 23-25 ATP
30% of energy from a glucose molecule is used to make ATP
When you are on a diet
You loose more metabolic water and breathe out more Co2
Poisons to Cellular Respiration (3 types)
- Block the ETC
- Respiratory Protein
- Uncoupler
Poisons that Block the ETC
- Rotenone
- Cyanides
Rotenone’s: Attach to the first protein in the ETC and block the transport of electrons so water or ATP is not produced. They are kill pests, insects and fish
Cyanides: Attach to cytochrome C. Inhibit the movement of electrons so no generation of ATP
Poisons: Respiratory Proteins
- Oligomycin’s / Malachite Greens
Block ATP Synthase. So everything is normal but H+ cannot diffuse through ATP synthase so no ATP production
Poisons: Uncouplers
- DNP (Dinitrophenol)
Makes H+ leaky so the concentration gradient. ETS continues but there is no ATP production
Dinitrophenol is used in people who go to the gym to increase their metabolic rate but this can be lethal.
Metabolic Pool
Carbohydrates, Fats and Proteins can be used to make energy in cellular respiration
Catabolism= Breakdown
Proteins and Nitrogenous Wastes
Proteins can be broken down to amino acids which contain amine groups. These amine groups then contain nitrogen which are called nitrogenous wastes.
- Ammonia- The most toxic
- Urea- (Used by humans) More energy expensive than ammonia but uses less water to get rid of
- Uric Acid- (Seagulls) Most energy expensive but takes the smallest amount of water to get rid of
In humans: We turn amino acids into urea through the Krebs cycle backwards which is called the Urea Cycle. Urea can then be exported through our urine.
Different R-Groups of amino acids can be processed differently and enter respiratory pathways at different sites
Fats
- Glycerol
- Fatty Acids
Glycerol: G3P can be converted into pyruvates
Fatty Acids: Carbon and hydrogen chains that become Acetyl CoA.
Related Processes to the Metabolic Pool
Glycogenesis: Production of Glycogen (Storage form of glucose)
Glycogenolysis: Break down of glycogen
Lipogenesis: Production of lipids. Caused by access carbohydrates that pyruvates and acetyl coA can be used to make fatty acids and stored fats
Lipolysis- Break down of lipids
Gluconeogenesis- Production of glucose from something other than carbohydrates. Fats and proteins turned into glucose and is done in the liver.
Metabolic Pool Overview
Proteins: Contain Amino Acids that can be used as pyruvate, acetyl CoA and in the citric acid cycle
Fats: Glycerol can be used as pyruvate. Fatty Acids can be used in acetyl CoAs.
Are Fermentation and Anaerobic Respiration the same thing?
NOO
Anaerobic Respiration uses a ETC pathway where fermentation does not
Fermentation is a anaerobic pathway
When Oxygen is Limited:
Hydrogens have no acceptors. NADH and FADH cannot be oxidized so they turn into free radicals. Glycolysis stops since there is no NAD
2 Things Organisms will do when there is no oxygen
- Anaerobic Respiration (Only done in prokaryotes)
- Fermentation
Anaerobic Respiration: Donate their electrons to a different receptor. Often Sulfur, Sulfate or Nitrate.
Fermentation: “Anabolic Pathway”- Runs without oxygen. Used for a quick burst of ATP but it is not sustained very long. Provides NAD so glycolysis can keep running
Zymology
The study of fermentation. Louis Pasteur is the first zymologist and you use this in alcohol fermentation.
Anerobic Respiration
Uses a different electron acceptor. Sulfate, Sulfur or Nitrate. This regulates the carbon, sulfur and nitrogen cycles. Still uses the ETC and ATP synthase.
- Is less efficient
-Is used in prokaryotes
2 types of Fermentation
- Lactic Acid fermentation 2. Alcoholic Fermentation
Lactic Acid Fermentation
Used in animal, bacterial (lactobacillus. yogurt and cheese) and fungi.
Pyruvate is reduced to Lactic Acid in the presence of lactate dehydrogenase. Then NADH is oxidized to NAD which is used to resupply glycolysis.
This Lactic Acid is then sent to the liver in order to make ATP in the Cori Cycle.
Drawbacks: A build up of Lactic Acid could disrupt your pH balance. Lactic Acid is going to accumulate.
Misconception: Lactic acid doesn’t cause cramps that is due to the oxygen debt build up in your muscles.
Alcoholic Fermentation
Used in yeast cells (Fungus). Used for bread and alcohol.
Pyruvate is decarboxylated to acetaldehyde and is then reduced to ethanol. NADH gets oxidized to NAD to resupply glycolysis by pyruvate dehydrogenase.
Ethanol and CO2.
Cori Cycle
Lactic acid turned into ATP in liver when O2 is present. Lactate is broken down to acetyl-CoA and metabolized.
Efficiency of Fermentation
2.1 efficiency compared to 29%. You have to repay off your oxygen debt.
Primary Metabolism
Involves the break down of nutrients in order to give building blocks and ATP. Dealing with the production of ATP. Catabolism= Breaking down
Secondary Metabolism
Synthesis of molecules that are not essential for cell structure or growth. They enhance survival and reproduction.
Common in Plants. Animals include the slow moving ones.
Important for: Defense, Attractions Protection and Competition. And for biopharmaceuticals
Categories
- Phenolics 2. Alkaloids 3. Terpenoids 4. Polyketides
Phenolics
Antioxidants with intense smells and flavors. Antioxidants help stabilize free radicals. Includes Flavonoids: Vanilla and Chocolate
Anthocyanins: Strong Pigment
Tannins and Lignin’s: Upset gi track
Alkaloids
Basic. Bitter Tasting molecules for defense.
Come from amino acid cursors. Include Caffeine, Nicotine, Capsaicin (spicy), Cocaine. Depressants: Morphine
Terpenoids
Biggest category of second metabolites. Intense smells and colors. Precursor for photoreceptors. Attractive. Mint, Cinnamon, Steroid Hormones
Polyketides
Chemical Weapons. Antibiotics (penicillin). Tetrodotoxin- Blue ringed octopus. Pufferfish. Conotoxin- Cone snail
Shuts off nervous system and provide pain relief
Before Division cells..
Grow, duplicate their organelles and replicate their DNA
Two Major Stages of cell cycle
Interphase (90%) and Mitosis (10%)
Why do we need the cell cycle?
Growth, cell replacement (from wounds) and Asexual Reproduction
Which cells do not divide and which divide frequently
Nerve, Skeletal + Cardiac Muscles cells do not divide
Red Blood Cells, Bone Marrow and Platelets regularly divide because they have a definite lifespan
G1
Cells are in recovery from previous division because division is very rough on cells. G1 is the longest phase in interphase (11 hours). They duplicate their organelles and make raw materials for DNA replication which includes Histones and Nucleotides
S
DNA synthesis. 8 Hours. Cells enter the S phase with one sister chromatid and leave with two connected at the centromere.
G2
Is only 4 hours. Is the phase that is after DNA synthesis and before mitosis. Generates raw materials for mitosis (microtubules)
M Phase
Only one hour. Mitosis is also called karyokinesis- which is the division of the nucleus. Daughter chromosomes are distributed to two daughter nuclei. Cytokinesis- Division of the cytoplasm. Cells like bone marrow do not go through cytokinesis
Cell Cycle Control
Signal- Molecule that inhibits or causes a metabolic event
External Signals: 1. Growth factors: Epidermal Growth Factor or Nerve Growth Factor (after a cut). Received at the plasma membrane and causes the completion of the cell cycle
G1 Checkpoint: Protein P53 at the G1 checkpoint will analyze the DNA in order to see if there is any damages to the DNA. It will signal repair enzymes. If the DNA cannot be repaired then it will undergo Apoptosis
Internal Signals: 1. Cyclin Dependent Kinases (CDKs). Enzymes that require the presence of cyclin. Usually are not active until they interact with cyclin
-Cyclin: Levels increase and decrease as the cell goes through the cell cycle. Interact with CDK in order to help guide the cell through the cell cycle. Without them the cells stops at G1,G2 or M. Allows for any damage to be repaired
MPF
Mitosis Promoting Factor
A specific Cyclin and Cyclin Dependent Kinase. When MPF reaches a certain amount this triggers the signal to start Mitosis.
S Phase Checkpoint
Replication Protein A: Molecule during the S phase that makes sure that all the DNA is replicated. No single strands of DNA. Can slow down the cycle in order for it to be completed
G2 Checkpoint
Mitosis will occur if the DNA is replicated properly. if it is not then apoptosis will occur. The MPF is in this checkpoint
M Checkpoint
Polo-Like and Aurora Kinases, look at the mitotic spindle and make sure that all the chromosomes are lined up properly. They can slow things down in order for fixing but if it isn’t fixed then apoptosis is undergone.
Eukaryotic Chromosomes (How they are structurally made)
Humans: 46 Chromosomes
1. DNA Double Helix
2. DNA wrapped around histone proteins that make Nucleosomes
3.Coiled Nucleosome
4. Loose Chromatin
5. Condensed Chromatin
6. Chromosome
Chromosomes: 60% histone proteins, 40 % DNA. Can be seen under the light microscope.
Condensed in order to prevent damage of the DNA during division
G1 Genetic material= chromatin
Chromosome Number in humans
46 Chromosomes. Diploid Organisms (Meaning they have 2 sets of chromosomes for each type) one maternal and one paternal
Egg and Sperm have one type each (haploid. n)
Karyotype: 1-22 Autosomes (Traits), Sex Chromosomes 23. Taken by a sample in White Blood Cells that are mid division so they are duplicated. Homologous chromosomes share the same traits (eye color) and are matched by 1. Size 2. banding 3. centromere
How duplicated chromosomes are held together
At the end of the S phase chromosomes are duplicated and held at the centromere by sticky proteins called cohesions. Kinetochore proteins attach to centromeres and attach the chromosomes to the kinetochore fibers .
Mitosis Overview
Centrosome located outside of nucleus and organizes the microtubule organization center (MTOC).
Centrosomes are replicated during S phase and there are 2 of them. 9 triplets of microtubules
As you enter the M phase chromosomes condense (2 sister chromatids are joined at the centromere)
Prophase
Longest phase in Mitosis. Nuclear Envelope disappears. Nucleolus Disappears. Spindle apparatus starts to form. Centrosomes start to move to opposite poles. Microtubules start to form an web array
Prometaphase
Centromeres are going to appear. Cohesions hold the centromere together and kinetochores connect to the centromere. Kinetochores attach chromosomes to the kinetochore fibers.
Aster Fibers- Connect chromosomes to cell membrane
Polar Fibers- Attach the poles to the mid line but are not touching anything
Metaphase
Kinetochore fibers add and subtract in order to put chromosomes aligned down the metaphase plate. In mitosis there should 46 chromosomes aligned
Anaphase
Shortest phase of mitosis. Polar fibers lengthen as fibers attached to chromosomes shorten so that sister chromatids can be pulled to opposite poles. Centromeres disappear.
Telophase
Opposite of Prophase. The nuclear envelope reappears , spindles disappear and chromosomes become chromatin. Centrosomes disappear
Cytokinesis
A contractile ring Actin filaments form the cleavage furrow which starts to form during anaphase. This allows both plasma membranes to be pulled apart until they break off each other. This is not done in all cells.
Prokaryotic Division
Happens in bacteria and is called binary fission. DNA is circular and folded in the nucleoid. Dna replication doubles the circular DNA. During division the DNA attaches to the plasma membrane. Splitting in 2 make identical cells. Exponential Growth because they can divide so fast. Asexual Reproduction
Apoptosis+timeline/process
Programmed Cell Death
Cells contain apoptosis enzymes called caspases which are regulated by internal and external factors. Different from necrosis which is cell death due to external factors such as toxins.
Mitosis and apoptosis are opposing forces.
Protein P53- During G1 checkpoint P53 2will check if there is damage to the DNA and if it cannot be repaired then it calls for apoptosis.
cell rounds–> chromatin condense-> plasma membrane blister—> consumed by lysosome
Pathways to Apoptosis
Extrinsic and Intrinsic
Extrinsic Pathway
Death ligand binds to death receptor which signals a series of caspases. They interact with mitochondria and the endoplasmic reticulum. These caspases destroy proteins for dna replication.
Intrinsic Pathway
UV, Radiation, Hypoxia (too little oxygen) and Chemo affects the mitochondria directly
- Endoplasmic reticulum stress due to misfolded proteins- affects ER directly When little oxygen mitochondria produce death substrates
Apoptosis Diseases
Too much: Alzheimer’s, Huntingtins and Parkinson’s
Too Little: Cancer, Autoimmune Diseases
Abnormal growth of cells is called a
neoplasm
Benign Neoplasms
Encapsulated. Non-cancerous. Do not invade cells near them. But benign neoplasms can turn cancerous if prolonged
Malignant Neoplasms
Not encapsulated. Invades neighboring cells. can dislodge and be left in other parts of the body (metastasis).
When it is cancer they doctor will survey adjacent lymph nodes in your body since lymph nodes can connect to your cardiovascular system and transport the cancer anywhere in your body
Carcinogenesis
Is the development of cancer. Tends to be gradual and is called acquired. Usually do not know it its present until it is obviously cancerous. This is caused by Carcinogens which are dangerous cancer causing chemicals. (UV, tobacco, alcohol)
Mutagens- Cause mutations in DNA. Most cancers have around 60 mutations. (X-Rays, chemical mutagens)
The immune system is older as you age.
Characteristics of Cancer Cells
- Lack of differentiation: Unspecialized
- Do not do normal functions (Larger nuclei which is based on amount of mutations)
- Have lost contact inhibition
- Metastasis (different architecture which is easy to fragment and causes the fragments to be moved through the body)
- Have a high metabolism which causes angiogenesis (the production of new blood cells) in order to keep the cancer cell nutrient. Cancer can also steal nutrients from neighboring cells
Cancer Cells Examples
Carcinomas: Tumors on coverings such as epithelial cells
Sarcomas: Tumors of connective tissue. Muscles and bones
Leukemias: Cancer in blood cells
Lymphomas: Cancer in lymph nodes
Cancer Origins
Proteo-oncogenes (normal genes) that stimulate the cell cycle from signals such as growth factors. Found at the end of stimulatory pathways. When the proteo-oncogenes are mutated they turn into oncogenes which cause the cell cycle to undergo continuously.
Tumor Suppressors- normal genes that when mutated leads to cell cycle loss of control and cause tumor formation
Normal-> Tumor-> benign (accumulates mutations)-> cancer-> metastasis-> death
P53- About 50% of cancers are caused by a mutation on the p53 gene which is at the G1 phase of interphase that checks for DNA. also the RB gene
Cancer Origins Telomerase
Telomerase- an enzyme that adds telomeres (repetitive sequences of nucleotides) at the end of a chromosome in order to make sure the DNA is protected. In each division the telomeres of chromosomes should shorten and these also shorten with age. When the telomeres are super short that chromosome no longer divides. Which is called Cellular Senescence.
85%-95% of cancers have a mutated telomerase gene that keeps on adding telomerases to the genes and makes the cell “immortal”.
Cancer Treatment and Causes
Surgery, Radiation, Chemotherapy, Immunotherapy, Hormonal therapy, Target
Causes- 90% is due to things in the environment. Multifactorial meaning that there are many things that make cancer
Over of Meiosis (not steps)
Meiosis means to make smaller
-Mitosis is a normal process and meiosis is very selective (only happens in sex cells)
Job is to reduce the chromosome number from diploid to haploid.
Homologous Chromosomes
Identified by
1. Appearance (banding)
2. Size
3. Centromere
Homologous chromosomes share the same traits but not the same form of those traits. trait=eye color, Allele/form= brown or blue
Meiosis 1 vs Meiosis 2
Meiosis 1= reduction division
Meiosis 2= equatorial division
Meiosis I
Prophase 1: Longest and most important phase of meiosis. Allows for genetic variation. Homologous chromosomes line up at the synapsis and are attached at the centromere using sticking proteins called cohesions.
The Synaptonemal Complex or Nucleoprotein Lattice are constructed by cohesions that align the chromosomes together. The same genes with same traits align with each other.
How does crossing over occur
Enzyme goes to the chiasmata and directly conducts crossing over so that the paternal and maternal DNA is given to each other.
-At the end of crossing over there should be 1: Fully Maternal 1: Fully paternal and 2: Mixed chromosomes
Crossing over happens around 2-3 times in animal cells but happens abundantly in plants. Crossing over increases as chromosomes increase in size
Prometaphase-> Metaphase I
Chromosomes attach to kinetochore and align at the plate
Metaphase differences between meiosis and mitosis
46- Mitosis
23 pairs of 2- Meiosis
Anaphase I
One homologous chromosomes gets pulled to opposite sides. Synapsis breaks up
Telophase I
haploid cells
Cytokinesis I
Ring made of actin filaments pull cells apart
Interkinesis
Similar to mitotic interphase. No DNA replication and its very short
Meiosis II
Indistinguishable from mitosis
Prophase: Nuclear envelope disappears, spindle starts to take form, centrioles separate and aster fibers spread out
Prometaphase: Kinetochores attach the sisters to fibers
Metaphase: 26 chromosomes on plate
Anaphase: Pulled apart
Telophase: Nuclear reappear, Centrioles disappear, spindle disappears
Cytokinesis- Pulled apart by cleavage furrow
produces gametes or germ cells
Genetic Variation
Genetic Variation that helps with environmental changes
1. Cross Over- At synapsis, nucleoprotein lattice and synoptical complex forms between homologous chromosomes
2. Independent Assortment- When they are aligned at the metaphase plate they can separate in any order.
3.Fertilization- When gametes form. there are 2^ 23 x 2^23 ways
Genetic Variation Significance
Asexual Reproduction- Is beneficial in a stable environment
Sexual Reproduction- If the environmental condition changes then this improves the chance of availability/ stability to the environment
Meiosis Vs Mitosis key points
Multicellular organisms and their zygote
have the same features and traits as their zygotes.
Meiosis produces..
Gametes called Gametogenesis
Spermatogenesis- Production of sperm
Oogenesis- Production of egg
In Spermatogenesis..
Cells lining the testes called primary spermatocytes are diploid cells. Primary spermatocytes are activated during puberty by testosterone. This causes primary spermatocytes to undergo meiosis I. After meiosis I they are secondary spermatocytes and haploid. Then they undergo meiosis II. This produces spermatids that have cannot swim because they are surrounded by a cytoplasm. They undergo maturation called spermiogenesis which gets rid of the cytoplasm and all its contents.
The final sperm has mitochondria in their midpiece and fructose in order to power the movement. The head has only paternal DNA. This allows it to move faster. the head contains a cap of enzymes called a acrosome which allows the enzymes to break off the egg covering during fertilization.
Men and produce sperm throughout their lifetime.
Oogenesis
Takes years to complete. Primary oocytes found in the ovaries get stuck in meiosis I. A female is born with all the eggs she will ever have. When the baby is one, she has all her cells stuck in this phase. Then at puberty estrogen and progesterone activate the primary oocytes to finish meiosis I. When the cells have finished meiosis 1, all the cytoplasmic contents surround one cell and the other gets get maternal DNA which is called a polar body.
Polar Body- Is infertile
When the egg is released from the surface it is arrested at metaphase 2 and is released once a month throughout the menstrual period (12years old- 40s)
When the cell is released it finished meiosis 1 and starts meiosis 2 but gets stuck at the metaphase 2 plate and flows down tubes until it is fertilized. If the egg meets a sperm then it will finish meiosis 2. Oogenesis produces only one good egg cell. The egg is full of cytoplasm with mitochondria so all mitochondria is maternal. In order to give the cell a start
Genetics
The study of genes and how they work
Gene- Unit of heredity. Basis of every characteristic
Sequence of nucleotides-> Genetic Difference-> Enzymatic Difference-> Difference in appearance
Early Ideas of Genetics
Hippocrates- Had the 1st known explanation of mechanism of hereditary. Believed in Pangenesis- “seeds” or particles collected and passed on to offspring resembled parents
Aristotle: Male and female sperm produced flesh and blood
Spontaneous Generation- Abiogenesis: Living coming from non living
Blending Concept of Inheritance: Parents of two different appearances will produce offspring of intermediate appearance
Experience Dependent Inheritance- Jean Lamarck. Species adapt to their changing environment. Behavior changes and modifies traits which are inherited by off spring
Gregor Mendel
“Father of modern genetics”. Formulated the fundamental laws of heredity. Followed the scientific method.
Removed the male anatomy and introduced pollen from other plant and looked at offspring (meiosis)
He had the right organism, experiment and analysis. Inheritance involves the reshuffling of genes from generation to generation.
Characteristics of Mendel’s experiment
Stem length, pod color, pod shape, seed color, seed shape, flower location, flower color
Dominant traits: Tall short, Green yellow, Inflated constricted, yellow green, round wrinkled, Axial terminal, Purple white
Gregor Mendel’s first generation
Tall plant vs short plant
Then he crossed F1 with F1 to get F2 which showed 3:1 ratio of dominance
Monohybrid Cross
Chose varieties that only differed in one trait
- “true breeding” same characteristics and self pollinate
Law of Segregation
Segregation of alleles.
Each individual has a pair of alleles. These alleles separate during gamete formation. Fertilization gives offspring two factors of each trait.
Alleles occur on homologous pairs at a certain gene locus.
Principle of Dominance
The dominant trait takes over the recessive
Punnett Squares
Follow the laws of Probability: Multiplicative Law (Chances of 2 independent events occurring together) and Additive Law ( how many times a particular event can be achieved).
Test Cross
A recessive phenotype will always have a homozygous recessive genotype
A dominant phenotype could have 2 genotypes
Test Cross: Uses a homozygous recessive plant to see if it is GG or Gg.
Dihybrid Cross
True breeding plants with 2 different types of traits (tall and green)
F1 Plants: Showed dominant (Tall and green)
F2 Plants had a 9:3:3:1 ratio. 9 Tall and green 3 Tall and yellow 3 short and green 1 short and yellow
Law of independent assortment
Genes on different homologous chromosomes so not affect each other an sort independently. The pair of factors of one trait separate differently than the factors of another.
Mendel Did not know: The closer the set of genes are on the same chromosomes the more likely they will be passed together to the offspring
Genetic Disorders methods
Karyotype: Shows chromosomal abnormalities
Pedigree: Shows generational genetic disorders
Amniocentesis
Genetic test in which amnionic fluid (fluid around the fetus) is taken and made a karyotype. This allows to see if there are chromosomal abnormalities, neural tube defects or genetic disorders. This test doesn’t say how severe the disorder is. 99% accurate. Takes a long time
Chronic Villus Sampling
Sample taken from the cells of the placenta. Can only do a karyotype and see chromosomal abnormalities, no metabolic disorders. Can be more risky but the results are faster.
Autosomal Dominant Disorders
AA= Lethal
Aa= affected
aa= not affected
Not super common
1. Most common is Achondroplasia (dwarfism)- Inability to turn cartilage into bone. Abnormality on chromosome 4.
Polydactyly- Extra finger
Neurofibromins: Tumors on nerves
2.
Autosomal Recessive Disorders
More common than dominant
aa= Affected
Aa= carrier
AA= not affected
1. Tay Sachs Disease- Very Fatal. Degeneration of the CNS. Chromosomal abnormality on chromosome 15. Missing an enzyme called hexokinase A which is found in lysosomes and are supposed to break down lipids. Lipids called ganglions start to cumulate and affect nerves and muscles.
Heterozygote Advantage- Against tuberculosis
2. Cystic Fibrosis- Mucinosis
Chromosomal affect on 7 and affects the CFTR (cystic fibrosis transmembrane regulator) affects the amount of chloride. Which then effects the amount of water and sodium in cells. Creates mucus which causes lung infections and affects the pancreas stopping enzymes from breaking down food for fuel. Infertile, poor growth.
Heterozygote Advantage: TB, cholera and typhoid.
3. Phenylketonuria (PKU)
Chromosomal abnormality of chromosome 12. Causes affects to enzyme Phenylalanine dehydroxylate. Phenylalanine cannot be metabolized which affects tyrosine. Tyrosine produces melanin so the person can have albinism. The person can also have poor teeth, hyperactivity and developmental delays.
Sickle Cell Amenia: Mutation in the HB gene located on chromosome 11. Causes RBC to have a sickle shape. Causes blood clots, anemia, infections and damage to organs. Heterozygote advantage against malaria.
Chromosomal Abnormalities
Polyploidy: Eukaryotes that are born with an extra set of chromosomes. Tripody: 3n and tetraploids (4n)
-Lethal in humans but is seen a lot in plants. Plants that have an odd number of chromosomes will spontaneously double to become fertile. Causes by nondisjunction during anaphase I
Aneuploidy: Either born with one missing or extra chromosome. Due to nondisjunction of meiosis I or II
Monosomy: (2n-1) Missing a chromosome of one type
Trisomy: (2n+1). One more
Nondisjunction
Primary Nondisjunction- Has to do with meiosis 1
Secondary Nondisjunction- Meiosis 2
Primary Nondisjunction- In Anaphase 1, it produces gametes with one more chromosome and one without that certain chromosome. The one that has extra is Disomic and the other is Nullisomic. Disomic makes 2 trisomy after meiosis 2. Nullisomic makes 2 monosomy cells after meiosis 2.
In Secondary Nondisjunction- Meiosis 1 is fine but in meiosis 2 sister chromatids do not separate properly so it makes 2 normal gametes. One monosomic and one trisomy.
Down Syndrome
Short, large tongue that makes speech impairments. 3 copies of chromosome 21. Not passed on by hereditary. 95% from nondisjunction. 5% from translocation in the 14/21 Robertsonian. Down syndrome is also in increased risk if the mother is passed normal reproductive age.
Edwards Syndrome
3 copies of 18th chromosome. Causes small jaw, clenched hands and lowered ears. Many die before birth
Plateau Syndrome
3 copies of 13 chromosome. cause brain defects, seizures, lowered ears and cleft lip.
Autosomes and Monosomy
Autosomes chromosomes 1-22 do not have monosomy because it is lethal
Turner Syndrome
Monosomy of the X chromosome. XO
90% of turner syndrome die before birth. Causes children to have normal intelligence, premature aging, widened chest and nipples. Lack of barr bodies. Barr body is a condensed x chromosome that shows no expression.
Klinefelter Syndrome
XXY or XXXY. Trisomy of the x chromosome. Only seen in males because the Y is still present. Testes and prostate have low developments. Makes the male look young
Jacobs Syndrome
Lack of reading and writing skills. Has trisomy of the Y chromosome. XYY or XYYY. No phenotype difference. No correlation between signs of a more masculine man.
Deletion
Part of the chromosome gets broken off. CAG-> CG
Duplication
Part is duplicated. CAG-> CAG
Inversion
Part of the chromosome is broken off at 2 spots. CAG-> GAC
Translocation
One part of a chromosome is broken off and is put on a non homologous chromosome.
Williams Syndrome
Very small deletion in the 7th chromosome that cannot be seen on a karyotype. Loss of elastin so this leads to premature ageing and cardiovascular issues.
Cri cu chat syndrome
Caused by a deletion of chromosome 5. Makes children sound like a cat call when they cry.
Wilms tumor and aniridia
Wilms tumor is cancer in kidneys of children. Aniridia is when the iris of the eye is missing and this is due to a missing piece of chromosome 11.
