Chapter 4 (21) Flashcards
replication
when DNA is copied before every cell division
transcription to RNA
when DNA is copied for instructions to be activated
DNA replication steps
- enzyme “unzips” H-bonds, separating strands
- new nucleotides are added by a second enzyme
- complementary base pairing ( A&T, C&G)
- proofreading & error correction
- Final enzyme seals breaks in backbone
- mutation if any change in sequence between original and final
what are the 4 categories of RNA
messenger, ribosomal, transfer, small RNAs
messenger RNA
carries copy of DNA template for translation into protein
ribosomal RNA
combines with proteins to make ribosomes
transfer RNA
transfers amino acids to ribosomes
small RNA
assist with making mRNA and rRNA
Transcription
making of mRNA in nucleus
steps of transcription
- enzyme unzips section of DNA
- complementary base pairing (but with U) from just one strand
- joining of nucleotides along P backbone
- Processing to mature
removing non-coding parts (introns) & leave only coding parts (exons)
add cap and tail to ends
Translation
turning mRNA into amino acid sequence in cytoplasm
translation steps
- mRNA has code-3 nucleotides are CODON for one amino acid.
- tRNA has anticodon to complement codon and carries one amino acid
- tRNA has anticodon to complement codon and carries one amino acid
- ribosome reads mRNA and has binding sites where codons and anticodons match up
p-site holds tRNA with polypeptide chain, A-site holds tRNA with next amino acid, peptide bond forms, P-site tRNA detaches, A-site tRNA moves over to P-site, repeat until termination signal
one mRNA can have many
ribosomes reading it at once
polypeptide chains must go through
further processing & folding to make working enzymes
what are the 4 types of tissues
connective, muscle, nervous, epithelial
connective tissue
“glue” of body
cells mixed with extracellular matrix of proteins and ground substances
protein fibers: collagen, elastic, reticular
ground substances: solid, fluid, semi-like
three types of connective tissue
fibrous, supportive, fluid
fibrous connective tissue
gelatinous matrix
loose fibrous- supports and covers many internal organs
dense fibrous- mostly collagen; tendons & ligaments
adipose-fat storage; beneath skin & around kidneys and heart
supportive connective tissue
solid matrix
cartilage: flexible; many fibers; joins, nose & ears
bone: rigid bc of inorganic salts; compact or spongy
fluid connective tissue
liquid matrix
blood-plasma & formed elements (red & white blood cells, platelets)
lymph: excess tissue fluid & white blood cells
muscle tissue
special fiber cells, contract when stimulated
three kinds of muscle cells
skeletal, smooth cardiac
nervous tissue
signaling and communication, neurons, neuroglia
neurons
conduct signals, dendrites, body, axon
neuroglia
support, insulate, protect, may speed signal
epithelial tissues
membranous or glandular
membranous epithelial tissue
simple or stratified (single/layered)
squamous, cuboidal or columnar (squashed/cubed collumn)
glandular epithelial tissue
exocrine, endocrine
endocrine glands have
no ducts, products are transported by bloodstream
skin is an organ system.. also a
integumentary system
functions of the skin
protects, regulates body temperature, and excretes
two layers of the skin
epidermis, dermis
what layer of the skin anchors
subcutaneous
epidermis
stratifies squamous epithelium hardened by waterproof keratin surface layers are dead new layers derived from basal cells also in deeper layers -langerhans cells: white blood cells that eat infectious agents -melanocytes-produce melanin -formation of vitamin D in UV light
dermis
beneath epidermis dense fibrous connective tissue -fibers give elasticity -blood vessels -sensory receptors
subcutaneous layer
anchors skin
loose connective & adipose tissue
-insulation
-excess fat storage
accessory organs of skin
nails, hair, sweat glands
nails
hardened with keratin, protect and sense for tips of digits, , grow from nail root
hair
dead cells filled with keratin, function in protection and sensing, grow from follicles in dermus-contain oil glands that make sebum, sebum lubricates & waterproofs, and inhibits some bacteria
sweat glands
make sweat, primary function to help cool body, also start in dermis, open to surface of skin, sometime into hair follicle
tanning occurs from
increase melanin production stimulated by sunlight
sunburn is due to
heat damage to skin cells
most organs are housed in _________ that are lined with ________
body cavities; membranes
homeostasis is maintained by
negative feedback mechanisms
