Midterm Flashcards
what are the key steps of cell formation?
- generation of self-replicating RNA
- production of proteins
- formation of cell membrane
what are the different adaptations of cells to different environments?
natural selection- random genetic variation that’s passed on from one generation to the next and by selection of cells that can survive the environment in which they live
archaebacteria- harsh environments such as ocean depths, salt brines, and hot acid springs. Some are even capable of converting carbon dioxide to methane.
Cyanobacteria- obtain their nitrogen directly from atmospheric N2
anaerobic bacteria- thrived hen the earth’s atmosphere contained very little oxygen
structure of nucleic acids: prokaryotic DNA and RNA vs eukaryotic
pro DNA: Circular DNA In cytoplasm
eu DNA: Long stretches of DNA containing coding and non-coding regions, organized as chromatin and located in the nucleus
pro RNA: RNA and protein in the same compartment
eu RNA: RNA synthesized in the nucleus, proteins in the cytoplasm
what makes anaerobic generation of ATP via glycolysis efficient?
Adding an oxygen-requiring step makes it highly efficient for extracting energy from food molecules beginning with the Kreb Cycle and ending with oxidative phosphorylation
what happens during oxidative phosphorylation?
NADH and FADH2 transfer the electrons that they have accumulated to molecular Oxygen and release a large amount of ATP
where do reactions like oxidative phosphorylation, kreb cycle, and glycolysis happen?
mitochondria
where is the energy for biosynthesis of cellular proteins, lipids, and other macromolecules derived from?
hydrolysis of ATP
how are Large proteins and nucleic acids assembled from small activated precursor molecules?
by repetitive dehydration reactions.
explain how food is broken down to generate ATP
- digestion: protein broken down into amino acids, fats into fatty acids, and polysaccharides into sugars
- smaller molecules enter cells and further degraded in the cytosol
- carbon and hydrogen atoms of sugars converted into pyruvate via glycolysis which enters the mitochondria where its converted to the acetyl groups of acetyl CoA
- acetyl CoA gives rise to a large amount of energy
- Oxidation of fatty acids can also give rise to acetyl CoA
- ATP is generated when the acetyl group of acetyl CoA is completely degraded to carbon dioxide and water
define catabolism
breakdown of larger molecules occurs due to the action of specific enzymes or a process
why do cells continuously use ATP?
to drive internal processes of macromolecular synthesis and breakdown
prokaryotic vs eukaryotic cells vs plant cells
plant cells: surrounded by cell walls with an underlying plasma membrane and they also have large vacuoles and specialized structures called chloroplasts that are essential for photosynthesis.
eukaryotic cell: have Nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus etc., animal cell: have a cell membrane and centrioles that play a vital role in cell division
aerobic metabolism
prokaryotic cell: doesn’t have Nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus etc., ex. bacteria
anaerobic and aerobic metabolism
what is chromatin?
chromosomal DNA within the nucleus in a tightly wound form that uses histone proteins
what is the nucleolus?
dense body which is the site of RNA assembly
what are nuclear pores?
openings in the nuclear envelope that allow for exchange of contents between the cytosol and nucleus
what is the nucleus?
regulates gene expression, coordinates protein synthesis and determines how a cell responds to a stimulus.
what is the endoplasmic reticulum (ER)?
series of membranous tubes or sacs that lies adjacent to the nucleus.
membrane is continuous with the outer membrane of the nuclear envelope.
why is the rough ER called “rough” and what does it do?
has ribosomes attached to its surface which are involved in active protein synthesis
lumen serves as the receiving site for the secretion of assembled peptide chains.
what is the smooth ER?
tubular and does not have ribosomes on its surface
plays a role in lipid metabolism.
what is the golgi apparatus?
system of stacked flattened sacs that help to modify, sort and package proteins and macromolecules and also prepare them for shipment to various parts of the cell for further processing or secretion via small vesicles
what are lysosomes?
membrane bound vesicles that contain hydrolytic enzymes that are responsible for intracellular digestion
what are peroxisomes?
membrane-bound vesicles but they contain oxidative enzymes that generate hydrogen peroxide and scavenge oxidative radicals.
what is the mitochondria?
sites of power generation for all eukaryotic cells.
how does mitochondria generate ATP?
by using oxygen and nutrient molecules
They contain a large number of enzymes that participate in redox reactions involved in the electron transport chain. This generates protons that drive the formation of ATP that is used as an energy source by the cell.
what is cytosol
liquid that contains various chemicals and macromolecules where the organelles are suspended
also contains filaments that give the cell its shape and helps with movement and cell division.
what is the cell membrane composed of?
two layers of lipids with a variety of proteins and carbohydrates incorporated into it
list the three major types of lipids that make up cell membranes
phospholipids
cholesterol
glycolipids
list the two ways amphipathic molecules will burry and protect the hydrophobic tails and leave the hydrophilic heads exposed to water.
- forming micelles – spheres with hydrophobic tails inward
- forming bilayers – with hydrophobic tails sandwiched together between the hydrophilic head groups
why is the formation of the lipid part of the biological membranes spontaneous?
due to the amphipathic nature of these molecules
when does flip flop movement occur?
when molecules from one side of the monolayer migrate to the other side (i.e: a molecule from the top half moves to the bottom). This type of movement occurs less frequently.