exam 2 Flashcards
organelles
organelles are defined as specialized structures that are separated from the rest of the cell by a phospholipid bilayer. have a more complex and well-developed subcellular architecture.
nucleus
5 microns in diameter providing genetic information to the cell (mainly nuclear chromosomes). The nucleus is surrounded by a double membrane called the nuclear envelope. site of all gene expression
nucleolus contains
active group of genes that encode and transcribe ribosomal RNA (the RNA component of ribosomes)
additional genetic information is also found
within mitochondria and chloroplasts)
Ribosomes
structures made of ribosomal RNA molecules and proteins and are the sites of protein synthesis in cells. NOT considered organelle (not enclosed in membrane) made of large and small component
Protein synthesis
mRNA travels from genetic material in nucleus to ribosome to tell it what to do…
Ribosomes in pro or eu?
Ribosomes are found in all cell types – both prokaryote and eukaryote. However, eukaryotic and prokaryotic ribosomes differ from each other enough that many of the antibiotics we use disrupt prokaryotic ribosomes but not eukaryotic ribosomes. Thus antibiotics kill bacterial cells but do not damage our cells.
endomembrane system
Protein production and modification usually takes place in a network of membrane-bound chambers called
endoplasmic reticulum
“network within the cytoplasm.”protein synthesis and modification begin here- 2 types (smooth and rough)
smooth endoplasmic reticulum
major role in synthesizing lipids and in degrading toxins.
rough endoplasmic reticulum
rough endoplasmic reticulum houses ribosomes on its surface, which is where many of the proteins targeted for export outside the cell are synthesized.
signal sequence
directs sorting of proteins in cell
translational complex
ribosome with an associated mRNA molecule
N-terminus
end that is synthesized first
signal recognition particle
binds to growing peptide with certain sequence at N terminus, facilitates association with rough ER
Golgi apparatus
processes proteins ,where carbohydrates are added to proteins
glycosylation.
where carbohydrates are added to proteins
cis face
side of the Golgi apparatus where proteins enter is re
trans face
shipping! where the transport vesicles “bud” out
secretory vesicle.
final transport vesicle that buds from the trans face of the Golgi apparatus. Secretory vesicles bind and fuse with the internal face of the plasma membrane by interacting with specific membrane protein
Hydrolases also known as hydrolytic enzymes
) are a general category of enzymes that have the ability to hydrolyze (decompose by reacting with water) various substrates.
Gangliosides
class of modified lipids that contain carbohydrates. prominent component of neuronal tissue, comprising about 6% of the total lipid content of the brain.
Hexosaminidase A
lysosomal enzyme that breaks down gangliosides. so they don’t accumulate ( control and breakdown)
Tay - Sachs disease.
homozygous recessive for allele that doesn’t create Hexosaminidase A- results in loss of motor skills beginning between three and six months of age with progressive evidence of neurodegeneration, including seizures, blindness, and eventual death, usually before four years of age, found often in Ashkenazi Jewish descent from founder effect
cytoskeleton is made up of three major components
microfilaments, intermediate filaments, and microtubules: support system and moves things around in cell
microfilaments
smallest cytoskeletal fibers made of polymerized subunits of the globular protein actin (like beads on a string) Microfilaments play a critical role in cell motility, where they facilitate cellular migration or, as in the case of muscle cells, contraction.
intermediate filaments
are somewhat larger than microfilaments, yet smaller than microtubules. Intermediate filaments are made of fibrous proteins wrapped around one another to form a thick, cable-like structure, supporting cell structures and anchoring organelles in the correct position within the cell. relatively static
Microtubules
largest cytoskeletal (we discuss) hollow tubes consisting of rows of paired tubulin molecules. Microtubules are important to major cellular events such as mitosis and meiosis and they also have a major structural role within the cell.
cancer drugs
target cytoskeletal b/c of importance in cell division, which is rapid in cancerous cells, unfortunately cytoskeletons are involved in healthy cells as well so these drugs harm all cells
Taxol
used to treat cancer (breast and lung) targeting tubulin and disrupting the mitotic spindle. This causes mistakes in chromosome segregation and cell division and eventually kills the cell
lysosome
Lysosomes are involved in breaking down materials in the cell. when vesicles bud off of the plasma membrane, bringing contents from outside the cell into the cytoplasm, they first fuse with lysosomes
hydrolytic enzymes
enzymes that hydrolyze/breakdown molecules- break down stuff in vesicles ONLY within lysosomes, become activated when they reach lysosome (inactive until then)
Mitochondria
converting the energy in food molecules into energy in the form of ATP, abundant in most eukaryotes (one or more per cell depending on how much energy is needed think muscles need thousands
Mitochondria are enclosed in a double membrane; a smooth outer membrane and an inner membrane that is contorted into a complex of infoldings called cristae. posses their own genetic material
ATP
high energy molecule that provides the energy for many cellular reactions
cristae (in mitochondria)
Cristae provide extensive surface areas for processes such as the electron transport chain, which takes place within the inner membrane This membrane typically contains thousands of copies of electron transport chain proteins. The space within the cristae is the mitochondrial matrix.
mitochondria contain circular DNA
Mitochondria and their genetic material are maternally inherited in sexually reproducing organisms. (The sperm mitochondria rarely enter the egg during fertilization.) Therefore, mitochondria are passed to offspring in the cytoplasm of ova. Hence, your mitochondria are virtually identical to your mother- maternally inherited diseases of consequence
Chloroplasts
double membrane-bound organelles found in plants and algae that are the sites of photosynthesis. The green color of chloroplasts comes from the photosynthetic pigment chlorophyll, chloroplasts have their own circular DNA molecule
endosymbiosis
one organism began living within the body of another.
endosymbiotic theory
mitochondria and chloroplasts evolved from prokaryotes that inhabited the cells of other larger prokaryotes. A relatively large prokaryote (a protoeukaryote)engulfed a smaller prokaryote (a protomitochondrion) accounts for inner membrane of mitochondria and outer mem. ++ (safe environment for respiration for ATP etc)
ancestors to the modern cells that possess both mitochondria and chloroplasts,
at some point in the past, underwent a serial endosymbiosis (sequential endosymbiotic events).
extant
currently existing
paraphyletic
descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
polyphyetic
members of groups are different protist lineages,