midterm 1 Flashcards
gestation
from when sperm&egg meet to birth
-9 month period
mesenchyme
fetal connective tissue where things will develop from
oogenesis
the formation of mature oocyte/egg from a small germ cell precursor during the embryonic period
ploidy
number
diploid cell
double the number of chromosomes found within a mature germ cell
-human cells are diploid with 23 pairs of chromosomes
haploid
one set of chromosomes
-formed by meiosis
germ cell
either the egg or sperm
somatic
the whole body besides reproductive areas
-so a somatic cell would be found throughout the body
germ
reproductive parts
-these are haploid
stages of development
fertilization (includes zygote, morula and blastocyst), pre-embryonic period, gastrulation, embryonic period and fetal period
fertilization
egg and sperm meet
-within ovarian cavity
zygote
single celled organism
-within ovarian/fallopian tubes
morula
formed after multiplication of zygote occurs
-within fallopian tubes
blastocyst
occurs when cells organize into inner and outer cell mass
-implants within uterus
pre-embryonic period
after fertilization to around the 2nd week
-main component is gastrulation
-germ layers form during this stage
gastrulation
when the germ layers are being developed and mature
-primitive streak is formed
-cell of the epiblast go to the streak
-invagination of these cells occurs and due to the outcome they will either become endoderm, mesoderm or ectoderm
-invagination occurs until the 4th week
3 germ layers
ectoderm : organs and tissues with contact to the outside world
mesoderm : organs and tissue internally
endoderm : GI tract
example of what develops from ectoderm
CNS, PNS, meninges, lens of eye, sensory epithelium of ear, nose and eyes
example of what develops from mesoderm
cartilage and bone, dermis, smooth muscle, blood and lymph nodes, kidneys, gonads and spleen
examples of what develops from the endoderm
epithelial lining of the respiratory tract, lymphatic cavity and eustachian tube
-big one is the GI tract
embryonic period
3rd to 8th week
-period of organ development
-nervous system development (from neural crest cells)
-cardiovascular system
-other organ systems (such as gut, urinary system and gonads)
fetal period
3rd month (9th week) to birth
-maturation of organs and tissues
-fetus looks more human
what do germ cells/layers give rise to
all fetal tissues and organs
how does exposure to teratogens affect the fetus in the embryonic period? fetal period?
embryonic period - death of could affect system wide/multi-system depending on when exposure occurs
fetal period - may interfere with growth and normal functions such as postnatal behavior
pharyngeal or branchial arches
what develops into major features of the ears, face and palate emerge during the embryonic period
what arches develop into all structures relating to the ear
1st and 2nd
how do the arches pair
there are arches 1-6
-arch 5 disappears
-4 and 6 then fuse together
what separates the arches
clefts and pouches
-clefts are external
-pouches are internal
what is a main reason why HL is a part of many disorders?
they develop from the 1st and 2nd arch which also develops many features of the face
how does the external auditory canal form
1 and 2nd arch cleft
-begins around week 6 with the invagination of the 1st cleft
-ends around week 26 with the recanalization of the connective tissue plug
-recanalization forms the canal BUT continues to mature until 6-7 years of age
how does the tympanic membrane/ear drum form
branchial membranes
-outer layer of membrane is ectodermal
-middle layer is mesoderm
-inner layer is endoderm (the lining of the tympanic cavity)
how does the tympanic cavity and eustachian tube form
pharyngeal pouches
-begins around week 8 and ends around week 21
-tubotympanic recess of the 1st pouch
-cilia within middle ear clears mucus and pathogens through the tube
how do the ossicles form
pharyngeal arches (1st and 2nd)
-starts with tubotympanic recess that are embedded within the mesenchyme
-during 8th month, cavity envelopes the ossicles resulting in a lever system
how do middle ear muscles and bones form
develops from pharyngeal arches
-1st arch leads to tensor tympani muscle, malleus and incus
-2nd arch leads to stapedius muscle and stapes
how does the pinna form
from size mesenchymal projections that develop from neural crest cells
-projections are called hillocks which are between the 1st and 2nd arches
-arrive during the 5th week and by the 7th week enlarge and fuse to form the pinna
development of the inner ear
22 days : otic placode appears and will thicken and invagination will occur
28 days : otic vesicle will separate from surface ectoderm
6th week : saccule forms a tubular in the low pole, which is the cochlea and after 8 week it will have 2 3/4 turns
9th week : mesenchyme surround inner ear labyrinth forms a capsule which becomes the petrous portion of the temporal bone
development of the cochlea
begins around the 10th week
-cartilage forms two spaces scale vestibuli and scala tympani)
-epithelial cells of the duct will form two ridges (tectorial membrane being one which houses OHC and IHC)
development of the vestibular system
around 6th week the SCC appear as pockets of the utricle portion
-central will give rise to canals
-one end of each dilates to form the crus ampullare
-macule in the utricle and saccule are sensitive to linear motion
difference between somatic and germ cell
somatic - throughout the body
germ - egg and sperm (can have new organisms develop from)
prokaryotic cell
not human
-no membrane bound nucleus or organelles
-most are bacteria
eukaryotic cells
human
-nucleus contains DNA
plasma or cell membrane
separates the interior of the cell from the outside
-controls the flow of molecules in and out
-prevents free flow
-bilayer of phospholipid molecules
explain the bilayer phospholipid molecules
hydrophobic fatty acid tails : facing inward
hydrophilic head : facing outward
mitochondria
battery of the cell and is a energy source that produces most of the ATP
-contains cristae where energy comes from
nucleus
largest and most prominent of the organelles
-responsible for growth and reproduction of the cell
-contains DNA
chromatin
contains genetic information that is organized in genes that determines the shape, structure and range of functions carried out by the cell
ribosomes
small particles that are made of RNA and protein
-found in the ER and free within the cytoplasm
-serves as a site of biological protein synthesis
what are the main phases of the cell cycle
interphase, mitosis/meiosis, cytokinesis
interphase
longest phase and is non-division
-at the beginning they are half the size of the parent cell due to just finishing mitosis
-G1 : bulking with doubling in size and RNA and proteins synthesize
-S : duplication of DNA
-G2 : growth
checkpoints of interphase
after G1 to make sure they are ready for DNA synthesis
after G2 to make sure cell is ready for mitosis
mitosis
division of the nucleus to replace dead or wounded cells
-prophase : x shape takes form due to coiling
-metaphase : centromere attachment occurs, move to center
-anaphase : centromeres break and they begin to move towards the poles
-telophase : arrive at poles and fibers disappear
cytokinesis
division of the cytoplasm
-fissure forms and allows for the separation into two cells
timeline of the cell cycle
interphase → G1 → (G0 → to cycle OR stays) → checkpoint → S → G2 → checkpoint → mitosis → prophase → metaphase → anaphase → telophase → cytokinesis → back to interphase and repeats
in what phase of the cell cycle do cochlear hair cells stay in?
G0 phase
-this is when a cell goes to the resting state and is either permanent or temporary
what is the end result of mitosis
2 identical daughter cells
-each with 46 chromosomes (23 pairs)
meiosis
division of germ cells
-chromosomes go through one stage of replication and two stages of division
phases of meiosis
meiosis 1 : ends with two cells that have all chromosomes still duplicated (2 copies of the parent DNA)
meiosis 2 : 4 daughter cells that are genetically different from the parent cells, with chromosomes with one copy of parent DNA
timeline of meiosis
interphase → meiosis 1 → prophase 1 → metaphase 1 → anaphase 1 → telophase 1 → meiosis 2 → prophase 2 → metaphase 2 → anaphase 2 → telophase 2 → cytokinesis
what is the end result of meiosis
4 non-identical daughter cells
differences between mitosis and meiosis
mitosis : somatic cells, replacing cells, two identical daughters, one cell division and diploid daughter cells
meiosis : gamete cells, four daughter cells, adds variations, two cell divisions, four haploid cells
similarities of mitosis and meiosis
-interphase, prophase, metaphase, anaphase and telophase
-cell division
-replication of genetic material
-both begin with a diploid cell
-each new cell has the same number of chromosomes
oogenesis
formation of female gametes
-during embryonic stage, germ cells differentiate into oogonia then divide by mitosis
-some will continue to go through mitosis
-oocytes then replicate DNA and increases
-primary oocytes remain in prophase and do not mature until puberty
(NOTES FOR MORE DETAIL)
end result of oogenesis
one mature egg from one primary oocyte
spermatogenesis
sperm cell production phase
-differentiation of germ cells begins at puberty
-primary spermatocytes enter prophase followed by meiosis 1 and the formation of secondary spermatozoa
-spermatids then undergo spermatogenesis
(NOTES FOR MORE DETAIL)
end result of spermatogenesis
production of mature spermatozoa
gene
physical unit of hereditary
-passed on
-made of DNA
-provides instructions to make proteins
allele
another word for gene
-alternate form for gene
nucleotide
building blocks for gene’s within a DNA molecule
-sugar, phosphate and a base
-creates a code that can create an amino acid
telomere
the cap on the end of a chromosome
-protective function for chromosomes
chromosome
DNA and its proteins are packed into this
-made of coiled DNA
-humans have 23 pairs of chromosomes (46 total)
-each pair has two short arms (p arms) and two long arms (q arms)
histone
what the DNA wraps around
nucleosome
when the DNA and histone combine
genotype
genetic makeup
-genotype determines a protein for function then there is a phenotype
phenotype
expression of genes
-manifest characteristic
karyotype
number and structure of the chromosome
-looking at the chromosome sets
deoxyribonucleic acid (DNA)
genetic code that determines characteristics
-made of nucleotides
structure of DNA
double helix
function of DNA
duplicates itself and to control development of the rest of the cell in a specific manner
-proteins carry this genetic code
what is DNA made of
nucleotide : one deoxyribose sugar, one phosphate group and one nitrogenous base
base parings
adenince and thymine (A & T)
cytosine and guanine (C & G)
DNA linkage
nucleotides chain together through covalent bonds to form polynucleotides
-polynucleotides are directional molecules due to have different ends
-one strand is 5’ and the other is the 3’
-the base connect in the middle and there is a sugar phosphate backbone
how is DNA different than RNA
bases : DNA has the T and RNA has the U
strand : double stranded for DNA and single stranded for RNA
sugar : deoxyribose for DNA and ribose for RNA (DNA missing the oxygen at 2’ and RNA has the sugar at 2’)
ribonucleic acid (RNA)
nucleic acid made of nucleotides that acts between the DNA and proteins
-vital for coding, regulation and expression of the genes
what is RNA made of
nucleotides : phosphate group, ribose sugar and a base
base pairings of RNA
adenine and uracil (A & C)
guanine and cytosine (G & C)
classes of RNA and their function
messenger RNA, ribosomal RNA and transfer RNA
messenger RNA (mRNA)
template that polypeptides are synthesized
-connecting link between the gene and amino acid
-in nucleus
ribosomal RNA (rRNA)
structural component of ribosomes
-performs functions in the ribosome that allow protein synthesis to occur
transfer RNA (tRNA)
brings amino acids into position along the mRNA template
what is a protein?
product of genes
-intermediate between genes and proteins
-each gene will code multiple proteins
what are amino acids?
there are 20 essential amino acids in the body
-made of an amino group, carboxyl group and an R group
-connected by covalent peptide bonds
-determine what protein is called for
what is the importance of methionine?
this is the start codon (AUG)
-what tells transcription to occur
what is transcription?
transferring of genetic information from DNA to RNA
-using one strand of DNA to produce a single strand of RNA
-3 phases
-opening up DNA (helicase) → initiation → elongation → termination → pre-mRNA → splicing of introns → mature mRNA
initiation
RNA polymerase binds to a certain nucleotide sequence and helicase will then unwind the DNA to expose the 3’ strand
elongation
bases will get encoded and the strand will grow
-RNA polymerase links the RNA nucleotides to form a RNA molecule
-uses the template strand (3’ strand) to form a complementary strand of mRNA to the coding strand
termination
terminator sequence tells the RNA to release from template strand and mRNA is release and the DNA recoils
-this is marked by a stop
-we get a pre mRNA which needs to take out the introns to become an mRNA
end result of transcription
a transcript in RNA language from DNA language
-mRNA strand
what is translation?
going from DNA language to mRNA protein language
-must go to the ribosomes within cytoplasm to become a protein sequence
-uses tRNA as an interpreter
tRNA within translation
match codon in mRNA with proper amino acids and to recognize the proper codon in mRNA
end result of translation
amino acid/protein
what are codons
group of 3 nucleotides that specifies for an amino acid
start codons
what signals for the beginning of translation to occur
-AUG
stop codons
what signals to stop the process
-UAA, UAG, UGA
difference between transcription and translation
-transcription takes it from DNA to mRNA and translation takes it from mrNA to protein
-transcription puts it in a new strand and translation takes that and makes a new language
how does DNA get to protein
DNA → transcribed → RNA → transcribed → protein → phenotype
antibiotics and genetics
antibiotics are chemicals produced by microorganism as a defense mechanisms against other microbes
-every step of protein synthesis can be inhibited by one antibiotic or another
epigenetics
study of how behaviors and environment causes changes that affect how genes work
-affects the phenotype NOT the genotype
epigenetics vs. genetics
epigenetic changes are reversible and do not change the DNA sequence
-this difference is not genetic
mutation
a permanent change in a genes biochemical makeup
-translocation : segments of a chromosome are swapped between gene
-duplication : a segment is repeated
-deletion : a segment is missing
-gene duplication and deletion : unequal crossing over
point mutation
the replacement of a single base nucleotide with another base nucleotide through insertions or deletions
-either in DNA or RNA
frame shift mutation
same as point mutations due to insertions or deletions of a single or more base pair
different types of point mutations
transition, transversion, nonsense, silent, missense, conservative and non-conservative
homozygous/homologous
the same
heterozygous/heterologous
different
syndromic conditions
HL/deafness may is only one of the group of medical problems a person has
-at least 2 systems are affected
nonsyndromic conditions
HL/deafness is the only system that is affected
-1 system affected
