Unit Test #1 Flashcards
What is a H-Bond and why is it possible?
Attraction force between a low electronegativity atom that is covalently bonded with a high electronegativity atom, with the O or N of the same or another molecule, because a low electronegativity atom will carry a partial positive charge when it is covalently bonded to an atom of higher electronegativity.
What is the difference between an hydrophilic and an hydrophobic molecule?
An hydrophilic molecule is and polar so it forms an H-Bond with water. On the other end, an hydrophobic molecule is non-polar so it doesn’t form an H-Bond with water.
What are the 4 macromolecules and their roles?
Nucleic Acids: Information
Proteins:Cell Machinery
Carbohydrates and lipids:
Energy, structure, cell signaling, membranes, etc.
Describe the 4 structures in macromolecules.
Primary: sequence of monomers
Secondary: general 3D form of a local segments within polymers (part of molecule)
Tertiary: Overall 3D structure of the polymer
Quarternary: arrangement of multiple polymers to form 1 functionnal group.
What is the name of the monomers of nucleic acids? What are the principle molecules of those monomers?
They are called nucleotides and they consist of:
1-Sugar molecule
2-Nitrogenous base on the 1’ carbon
3-Phosphate group on the 5’ carbon (outside of the ring)
What is the difference in the monomer of DNA and RNA?
The sugar molecules aren’t the same.
-DNA is compose of a deoxyribose
-RNA is composed of a ribose which has 1 more oxygen than deoxyribose.
What are the 5 nitrogenous bases?
Pyrimidines (1 ring):
-Cytosine
-Uracil
-Thymine
Purines (2 rings):
-Guanine
-Adenine
What are the nitrogenous bases pairs?
DNA:
Adenine pairs with Thymine
Cytosine pairs with Guanine
RNA:
Adenine pairs with Uracil
Cytosine pairs with Guanine
What is the central dogma with nucleic acids?
DNA (information storage) is transcript when thymine is replaced by uracil to become mRNA (info carrier) then mRNA is translate to protein (active cell machinery).
What are the 5 groups in amino acid molecules?
There is the side chain (R). An amino group, a central carbon, a carboxyl and a hydrogen.
What are the 3 types of R groups?
Non-polar:
Always CH bonds ➡️ Hydrophobic
Polar:
Hydrophilic
Charged:
Electrical charged ➡️ hydrophilic
What is the primary structure of proteins?
Peptide links between C-N. (N terminus to C terminus.
What is the secondary structure of proteins?
Alpha:
Helix
Right-handed coil resulting from H-Bond
Beta:
Pleated sheet
2 or more polypeptide chain aligned
What is the tertiary structure of proteins?
Interactions between R-Groups ➡️ subunits.
It give the shape of the molecule
What is the quaternary structure of proteins?
Overall protein that is compose of 4 subunits
Why do carbohydrates have so much energy?
They have H-C-OH bond which have high potential energy. For every C there is an O.
What is the difference between the isomers ⍺ glucose and the β glucose?
⍺ Glucose: OH isn’t in the same plane as 6’ carbon
β glucose: OH is in the same plane as 6’ carbon.
What is the difference between the isomers ⍺ glucose and the β glucose in there functions?
⍺ links: energy storage
Starch (plant) and glycogen (animal)
β links: Structure
Cellulose (plant), chitin (animal, fungus), peptidoglycan bacteria
Describe the β links particularity.
There are straight chains held by many H-Bonds ➡️Highly pack which gives a fibrous structure. Also, glycosidic linkages are difficult to hydrolyze. That’s why, animals have enzymes in there stomachs.
What are the specificities in the lipid molecules?
They have C-H bonds and a little amount of O compared to carbs.
Non-Polar, so insoluble in water
Describe triglycerides molecules structure.
It is 3 fatty acids link with glycerol.
Fatty acids: a lot of C-H bonds
Triglycerides: energy and insulation ➡️ fats and oils.
What are the proteins in steroids?
Hormones, vitamines and membranes
What is the particularity of phospholipids?
There is 2 fatty acids and one phosphate linked to glycerol. This gives an amphipathic molecule.
Fatty acids: hydophobic
Phosphate: hydrophilic
What is the particularity of membranes?
Cell membranes are semi permeable
Hydrophobic molecules get through
Small, uncharged polar molecules ➡️ possible to get through
Large, uncharged polar molecules ➡️ repel
Ions ➡️ don’t get through at all
Processes in which macromolecules are crossing the membrane.
Taken: endocytosis
Excreted: exocytosis
Describe phagocytosis.
Large molecules or entire cells are engulfed (endocytosis for large things).
Why are cell small?
They are limited:
-Surface area/ volume ratio
-Volume ➡️ stock inside cell
-Surface area ➡️ Interact with environment
What is ATP?
Adenine Triphosphate:
-Cell’s energy currency
-Energy in C-H links
-5 carbon with 3 phosphate group
Summarize the cellular respiration equation.
Sugar+ O2 ➡️ CO2 + H2O + Energy (ATP)
Summarize the photosynthesis equation.
CO2 + H2O + Light ➡️ CH20 (carbs) + O2
Describe plasma membrane and its role.
Phospholipid bilayer:
-Allows cell maintain constant internal environment
-Selectively permeable barrier
-Important in communication and receiving signals
-Often has proteins for blinding with adjacent cells
Describe nucleus and its role.
-Contains DNA
-DNA replication
-Nucleolus ➡️ assembly of ribosomes
-Genetic control of cell activities
Describe ribosomes and its role.
Protein synthesis
Describe the endomembrane system and the organelles in it.
Attach to nucleus.
-Endoplasmic reticulum
-Golgi apparatus
Describe rough ER and its role.
-Break new proteins
-Modify and transport proteins
Describe smooth ER and its role.
-Chemically modifies small molecules (drugs and pesticides)
-Hydrolysis of glycogen
-Synthesis of lipids and steroids
Describe Golgi apparatus and its role.
-Receive proteins from ER
-Concentrates, packages and sorts proteins
-“Ships” to appropriate location proteins
-Polysaccharides for cell walls are synthesized (plant)
Describe lysosomes and its role.
Comes from Golgi
-Contain digestive enzymes
-Hydrolysis of macro to monomers
Describe mitochondria and its role.
Double membrane, makes its own proteins and ribosomes.
-Fuel molecules (ATP)
Describe chloroplasts and its role.
Double membrane and makes its own ribosomes.
-Site of photosynthesis
Describe vacuoles and its role.
In plants.
-Structure
-Store waste products and toxic compounds
Describe cytoskeleton and its role.
Made of microfilaments, intermediate filaments and microtubules.
-Supports and maintains shape
-Positions organelles
-Allows some types of movement
-Some fibers act as support for motor proteins
-Interacts with extracellular structures to hold cell in place
Describe centrosomes and its role.
Microtubules.
-Makes mitolic spindle
What is the goal of cellular division?
Unicellular organisms:
-Reproduction
Multicellular organisms:
-Reproduction
-Growth
-Repair
What is the difference between mitosis and meiosis?
Mitosis:
-Division of somatic (non sex) cells
-Asexual reproduction (cloning)
-Tissue repair
-Body growth
-Replace worn out cells
Meiosis:
-Division of germ (sex) cells
-Sexual reproduction: formation of eggs in ovaries or sperms in the testes
What are the 4 events that have to occur for cell division?
-Reproductive signal: to initiate cell division
-Replication of DNA
-Segregation: distribution of the DNA into 2 new cells
-Cytokinesis: separation of the 2 new cells (actual process of division)
Describe the 3 phases that occur before mitosis in the cell division cycle.
G1: Cellular growth and maintenance
S: DNA makes a copy of itself
G2: growth and preparation for mitosis (duplicate centrosomes)
What is making advance the division cell cycle in between phases?
Chemical substances trigger from one phase to another
-Can be initiated internally or can be (reproductive) signals from other cells
-Based on needs of the WHOLE organism
Definite ploidy.
It is the number of sets of DNA.
n=1 complete set of DNA
Definite diploid cells.
2n
Refers to cells that contain 2 sets (one from each parent)
Definite haploid cells.
n
Refers to cells that contain one set of DNA
↪️Humans: gametes (sperm and egg)
Definite homologous chromosomes.
-Same chromosome from different set
-One of maternal and one of paternal origin
-Same shape, length and assortment of genes
↪️ Allele: different versions of a gene
What is the difference between mitosis and cytokinesis?
Mitosis: separation of nucleus
Cytokinesis: separation of cytoplasm
Describe prophase in mitosis.
-Chromatids condense and become visible
-Nuclear enveloppe and nucleoli disappear
-Centrosomes go to poles and make microtubules (spindle)
↪️Polar microtubule: overlap in center
↪️Kinetochore microtubules: Attach to chromatids
Describe metaphase in mitosis.
-Centromers go in equatorial plates
Describe anaphase in mitosis.
-Sister chromatids separate and move to opposite ends of spindle
Describe telophase in mitosis.
-Spindle breaks down
-Chromosomes uncoil
-Nuclear enveloppe and nucleoli are reformed.
Describe cytokinesis.
Division of cytoplasm.
Describe meiosis.
-Takes 2n cells
-2 nuclear divisions, DNA duplicated only one time.
-Result: 4 genetically novel haploid cells.
Describe prophase 1 in meiosis.
Homologous chromosomes pair up.
Describe anaphase 1 in meiosis.
Homologous chromosomes separate and move towards opposite ends of the ce
What are the two sources of genetic variations?
-Crossing over
-Independent alignment.
Describe the characteristics of independent alignment.
-Independent random positioning of homologous pairs on metaphase 1
-50/50 chance of daughter cell getting particular parental chromosome
Describe nondisjunction.
Chromosomes or chromatids do not pull apart at anaphase 1 or 2.
-Aneuploidy: chromosomes lacking or present in excess.
-Polyploidy: nondisjunction over complete set 3n,4n, 5n…
