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Anatomy
Chapter 3 Cells: The Living Units
Question | Answer |
---|---|
smallest structural and functional living unti | cell |
flexible outer boundary, composed of lipids and proteins | plasma membrane |
intracellular fluid containing organelles | cytoplasm |
control center of cell | nucleus |
important for membrane structure | lipids |
various signaling and transport functions | proteins |
function: transport, receptors or enzymes, attach to cytoskeleton or other cells | membrane proteins |
3 types of membrane junctions | tight, desmosome, gap |
impermeable membrane junction | tight junction |
anchoring membrane junction, binds cells | desmosome |
communicating membrane junction | gap junction |
membrane transport | membrane is selectively permeable |
no cellular energy(ATP) required, moves down concentration gradient | passive transport |
type of passive transport | osmosis |
the diffusion of water across selectively permeable membrane | osmosis, occurs until equilibrium is reached |
measure of total concentration of solute particles | osmolarity |
where the solute concentration is equal to cytosol | isotonic |
where the solute concentration is greater than cytosol | hypertonic, wrinkled |
solute concentration is less than cytosol | hypotonic, bloated |
requires carrier proteins, moves against gradient, uses energy(ATP) to move molecules | active transport |
transport of large particles, macromolecules and fluids across plasma membrane, requires energy(ATP) | vesicular transport |
2 types of vesicular transport | exocytosis and endocytosis |
powerhouse of cell, provides most of cells ATP, has it's own DNA and RNA | mitochondria |
endomembrane system contains | nuclear envelope, rER, golgi body, vesicles, lysosomes |
contain protein and rRNA, site of protein synthesis | ribosomes |
interconnected tubes, continuous with nuclear membrane | endoplasmic reticulum |
storage and transport of proteins, has ribosomes | rough ER |
site of steroid and lipid synthesis, no ribosomes | smooth ER |
UPS of cell, modifies, concentrates and packages proteins and lipids | golgi apparatus |
cell stomach, contains digestive enzymes | lysosomes |
series of rods, important for vesicle transport and cell movement | cytoskeleton |
tough rope-like protein fibers, resist pulling on cell, attach to desmosomes | intermediate filaments |
dynamic hollow tubes, radiate from centrosome, determines shape of cell and placement of organelles | microtubules |
2 types of cellular extensions, whip-like extensions on surfaces of cells | cilia and flagella |
moves substances across cell surfaces | cilia |
propels whole cells (sperm) | flagella |
brain of cell, blueprints for cellular proteins, signals for protein synthesis | nucleus |
double-membrane barrier with pores | nuclear envelope |
cell cycle | changes from formation of cell until it reproduces |
interphase | period from cell formation to cell division |
subphases of interphse | G1 for growth, S for DNA synthesis, G2 for growth and prepping for division |
DNA replication | DNA helices unwind from nuclesomes, leicase enzyme untwists double helix |
nucleotide strand | each is a template for building a new complementary strand for DNA replication |
replisome | site of DNA replication |
DNA polymerase | only works in one direction |
semi-conservative DNA replication | continuous leading strand is synthesized discontinuous lagging strand is synthesized in segments DNA ligase splices together short segments of discontinuous strand =2 DNA molecules formed from original |
mitotic phase | cell division |
4 stages of mitosis | prophase, metaphase, anaphase, telophase |
cytokinesis | division of cytoplasm by cleavage furrow |
chromosomes become visible, each with 2 chromatids joined at centromere | prophase |
centrosomes separate and migrate toward poles | prophase |
mitotic spindles and asters form | prophase |
nuclear envelope fragments | prophase |
kinetochore microtubules attach to kinetichore of centromeres and draws them toward equator | prophase |
centromeres of chromosomes are aligned at the equator | metaphase |
metaphase plate | plane midway between poles |
shortest phase | anaphase |
centromeres of chromosomes split, chromatid becomes chromosome | anaphase |
chromosomes are pulled toward poles by motor proteins of kinetochores | anaphase |
polar microtubules continue forcing poles apart | anaphase |
begins when chromosomes stop moving | telophase |
2 sets of chromosomes uncoil and form chromatin | telophase |
new nuclear membrane forms around each mass | telophase |
nucleoli reappear | telophase |
spindle disappears | telophase |
begins during late anaphase, ring of actin microfilaments contracts to form cleavage furrow, 2 daughter cells are pinched apart, each with a nucleus identical to original | cytokinesis |
segment of DNA with blueprint for 1 polypeptide | gene |
protein synthesis | triplets of nucleotide bases form genetic library; each triplet specifies coding for one amino acid |
transfer DNA gene base sequence to a complementary base sequence of mRNA | transcription |
base sequence, promoter | transcription |
enzyme that oversees synthesis of mRNA | RNA polymerase |
3 steps of transcription | initiation, elongation, termination |
RNA polymerase binds to promoter, pries apart 2 DNA strands and initiates mRNA synthesis and start point on the template strand | initiation of transcription |
RNA polymerase moves along template strand, elongating mRNA transcript one at a time, unwinds DNA double helix and then rewinds behind it | elongation |
mRNA synthesis ends when termination signal is reached. RNA polymerase and completed mRNA transcript are released | termination |
converts base sequence of nucleic acids into amino acid sequence of proteins (genetic code) | translation |
involves mRNA, rRNA, and tRNA | translation |
carries instructions for building a polypeptide | mRNA |
structural component of ribosomes, helps translate message from mRNA | rRNA |
bind to amino acids and pair with bases of codons of mRNA and ribosome to begin protein synthesis | tRNA |
complementary 3 base sequence on mRNA | codon |
used to convert nucleic acids to a specific amino acid | genetic code |
translation | mRNA attaches to small ribosomal subunit, moves along mRNA to start codon large ribosomal unit attaches, forms functional ribosomes anticodon of tRNA binds to its complementary codon and adds its amino acid to the forming protein chain |
translation | anticodon of tRNA binds to its complementary codon and adds its amino acid to the forming protein chain new amino acids are added by other tRNAs as the ribosome moves along rRNA until it reaches stop codon |
role of rER in protein synthesis | mRNA-ribosome complex is directed to rER by signal recognition particle forming protein enters ER sugar groups may be added to protein and alter shape protein is enclosed in a vesicle for transport to golgi body |
prevents protein coding RNA from being translated | antisense RNAs |
small RNAs that interfere with mRNAs made by certain exons | micro RNAs |