Developmental Biology Exam 1

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zygote

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formed from the maternal egg and paternal sperm

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gamete

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maternal egg and paternal sperm

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stem cells

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early embryonic cells, can develop into any kind of tissue

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somatic chromosomes

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46 chromosomes(diploid), 23 pairs(haploid)

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reproductive chromosomes

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have 23 chromosomes

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Down syndrome

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Trisomy 21, increase chance with maternal age, mild to moderate cognitive delays, facial features, heart defects, hearing problems, alzheimers, leukemia, thyroid conditions

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Genome

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sum total DNA content, DNA codes for specific genes, blueprint for building proteins

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nucleotide bases

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ATCG

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exons

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regions that actually code for proteins

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introns

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regions that are non-coding(dont know the purpose)

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promoter region

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tell the beginning and end of gene segments and translation(create a protein from that piece of DNA

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Amino acids

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20 amino acids build all proteins in the body

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codons

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code for amino acids in sets of 3 nucleotides in the mRNA

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Gene expression

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not all genes are expressed or are making proteins, all cells have all genes, but different cells express different genes/make different proteins; testing which genes are expressed in which tissue requires samples of each tissue

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Animal models for knock-out/knock-in

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almost all knock-out died, if knocked-out later not all died

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Gene mutation

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a permanent change in the DNA sequence

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inheritance

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mutations in reproductive cell lines are passed to offspring; typically small scale mutations

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22q11.2 deletion syndrome

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DiGeorge syndrome; missing section of chromosome 22 in all cells; congenital heart disease, cleft palate, immune problems, heart defects, growth delay, hearing loss, speech and cognitive delays, autism, ADHD, anxiety ; not inherited; large scale mutation

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Polymorphism

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mutation present in a frequency of 1% in population, most without obvious relevance to health or disease, presence necessitates that at least 2 forms of that chunk of DNA exist with at least 1% frequency in the pop.

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Missense

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change in one nucleotide results in a different amino acid which will change the protein generated; changes meaning of the sequence

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Silent

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change in one base makes no change in amino acid coding

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Nonsense

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change in one base results in a stop codon before the protein is complete

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Frameshift

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addition of one or more bases results in new combinations of triplets, changing the codons completely

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De Novo Mutation

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error in DNA replication during early prenatal development

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Mutagen

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exposure to mutagens like UV rays, radioactivity, certain chemicals that can bind to or damage DNA

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proof readers

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body's natural protection against mutagens to check DNA sequence during replication to catch errors, preventing potentially deadly accumulation of mutagens

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Genotype

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at any one locus on a chromosome, each individual has 2 copies of the gene or DNA sequence, the two copies may be identical alleles(homozygous) or the common allele paired with a polymorphism(heterozygous); refers to the patterns of allele pairs that an individual has at a specific locus

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alleles

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homozygous- identical alleles in both chromosomes

heterozygous- polymorphisms of the allele in the chromosomes

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Phenotype

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observable characteristics of an individual;

physical-hair, eye color, height

biochemical-blood type, metabolism

disease status- sickle cell anemia, diabetes

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mendelian inheritance

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if you have the gene you have the disease, if not you dont

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Autosomal dominant

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one gene causes the phenotype, only need one

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autosomal recessive

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need two copies, if you have 1 you are a carrier, not mendelian

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X-linked dominant

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all carriers will be affected

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X-linked recessive

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all male carriers affected; females need 2 copies

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Concordance heritability

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similarity in phenotype between two individuals

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co-twin studies

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one twin is control to look at other(one being a smoker)

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Heritability

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degree to which individual differences in a trait can be accounted for by individual differences in genetics

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genotype

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environment correlations

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Passive

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parents have the genetic trait and provide the environment to support the trait

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reactive

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parents notice genetic trait and react in way that supports the trait

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active

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child picks environment that supports their genetic trait

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vulnerability hypothesis

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some genetic variants may put an individual at risk for a particular trait or outcome but needs a specific experience or environment

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plasticity/sensitivity hypothesis

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some genetic variants make an individual more sensitive to differences in the environment

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Epigenetics

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study of heritable changes in genome function that occur without a change in DNA sequence

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DNA methylation

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methyl groups attach to DNA sites to turn off expression of the gene

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Histone modification

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histones are proteins that help compact the DNA strand in the cell nuclei, histone modification can lead to relaxing or tightening of the DNA coil

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Neurons

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broad class of cells that are the building blocks of the brain

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cell body

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holds the nucleus

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nucleus

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holds the DNA

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dendrite

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feels out the environment of the cell, looks for chemical signals, is a listener

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Axons

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communicate info with other cells

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axon terminals

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ends of axons that are close to the dendrites of other cells

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myelin sheath

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increases the communication speed of axon

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synapse

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the connection made between the pre-synaptic cell and post-synaptic cell

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synaptic cleft

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the gap between the two cells, as they don't touch

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receptor

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on post-synaptic cell, with specific areas sensitive to a specific type of neurotransmitter chemical

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synaptic vesicle

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packages that hold the neurotransmitters and travel with them all the way from the cell body to the axon

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neurotransmitter

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chemical molecules that communicate signal along the neuron

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oligodendroglial cells

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myelin; wrap themselves around axon to increase speed of signals

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Anterior vs Posterior

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front vs back

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superior vs inferior

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top versus bottom

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lateral vs medial

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outside vs inside

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dorsal vs ventral

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top of brain to back of spine and bottom of brain to front of spine

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sagittal

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slice in half giving two sides

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coronal

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slice giving front and back

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horizontal

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giving top and bottom

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Gray matter

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holds info

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white matter

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highways

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gyri

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tops of brain folds

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sulci

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bottoms of brain folds

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central sulcus

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separates front and back

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sylvian/lateral fissure

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separates frontal and temporal lobe

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longitudinal fissure

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separates hemispheres

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transverse fissure

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separates cerebrum from cerebellum

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ectoderm

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nervous tissue

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mesoderm

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muscle and connective tissue

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endoderm

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internal organs

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neurulation

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neural tube formation- formation of cells that will become the nervous system

1. neural plate forms

2. neural tube begins to fuse shut at tay 21 starting at rostral end and closes at caudal day 25

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cranioarchischisis totalis

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failure of entire neural tube to close

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anecephaly

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failure of rostral end of neural tube to close

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spina bifida

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failure of caudal neural tube closure

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myelomeningocele

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protrusion of nervous tissue outside of the body

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Germinal matrix

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cell layer that lines the ventricular zone where new neurons arise

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stem cells

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precursor cells

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microencephaly

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smaller brain, germinal layer is exhausted early, fewer cells, IQ decrement, may be caused by either genetic mutation or environmental toxin exposure

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macroencephaly-

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enlarged brain, too many cells produced/ cells have longer axons/dendrites, wide range of functioning, associated with some genetic disorders

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migration

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after cell is done dividing it migrates to form cortical plate which becomes gray matter of cortex

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radial glia

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fibers that future neurons climb onto to migrate radially toward the surface

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reelin

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guide for migrating cells

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lissencephaly

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neurons fail to migrate through earlier layers to form 6-layered cortex; leaves smooth brain, no gyri/sulci, total lack of reelin

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schizencephaly

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agenesis of a portion of the germinal zone; lack of neurogenesis so lack of migration; gray matter clefts occur, germinal matrix failed to generate neurons to go to particular parts of the brain; possibly caused by abnormal reelin and disrupted cell migration

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differentiation

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development of the characteristics of a particular cell type

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neurites

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precursors to axons and dendrites that project from the cell body

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cytoskeleton

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structure of cell; made up of

actin- protein that comprises cytoskeleton on outer edges of cell; and

microtubules- protein of cytoskeleton that get built into axons and dendrites that is the physical structure of the axon

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growth cone

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tip of axon on migrating immature neuron that leads to axon growth

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filopodia

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finger like structures(sense local movement)

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lamellipodia

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fan like membrane structures(sense local environment

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corpus callosum dysgenesis

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disorder of axon development; malformation of corpus callosum

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dendrite development

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begins at 15 weeks and increases during 3rd trimester and postnatally

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dendritic spines

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small protrusion from dendrite that will be the site of a future synapse

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fragile X, autism, muscular dystrophy

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disorders of dendrite developmnt

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apoptosis

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massive programmed cell death of 40-60% of cells, eliminates neurons with inappropriate connections and helps result in optimal number of each cell type

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synaptogenesis

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formation of synapses between neurons in the nervous system, highly specific connections;

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errors in synaptogenesis

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same as dendritic development

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myelin

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lipid which wraps itself around axons as form of insulation; starts at end of prenatal period and ends in middle age

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radial glia

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guide neuronal migration

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microglia

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remove dead cells

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astrocytes

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impact communication between neurons

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hypomyelination

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caused by iron deficiency causing slower speed of info processing/signal failure

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multiple sclerosis

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autoimmune disorder that onsets in early adulthood and is associated with demyelination

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plasticity

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capacity of the brain to adapt or change in response to chemicals, activity, or other input/experience

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Types of plasticity

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recover or sparing of function, critical or sensitive periods, synaptic plasticity

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cortical reorganization

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ability of brain to change neuronal connections due to accidents etc...

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Rasmussen's encepalitis

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seizures, loss of motor skills and speech, hemiparesis, dementia; either viral infection or autoimmune/ can be treated with hemispherectomy

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experience-expectent plasticity

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development based on the expectation that appropriate environments will provide information needed to select appropriate subsets of synaptic connections, common to all species members

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experience-dependent plasticity

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unique to each individual, active formation of new synaptic connections throughout the lifespan based on each person's unique interactions with their environment

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sensitive period

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period of time when incoming stimuli and experiences have greatest impact on development,

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Long-term potentiation

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long lasting enhancement of neuronal responding, thought to be neurobiological mechanism for human learning and memory

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electroencephalography

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measures electrical signal produced by small populations of neurons; within dwelling electrodes; precise timing, weak in brain localization

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Event-related potentials

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EEG in response to a certain stimulus, focuses on precise timing

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CT scan

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produces 3-D image of body part, examines tumors, brain injury, pain, small x-ray used; little time; sensitive to movement; only structure

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PET

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imprecise temporal information over minutes; radiation; expensive; measures metabolic activity of brain , good spatial resolution, more direct measure of energy use by neurons, provides baseline measure of brain activity

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MRI

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Measures time for protons in differing tissues to return to previous angle; limited temporal resolution; very precise spatial location, info on structure and function

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fMRI

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measures changes in blood oxygenation

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DTI

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measures water movement in brain

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NIRS

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limited to surface regions; looks at blood oxygenation in cortex; balances spatial and temporal resolution

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TMS

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very expensive; treats depression; measures brain response in manipulated behavior

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Placenta

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Metabolizes nutrients and energy

bidirectional transport

barrier against toxins

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error of commission

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occur when developing brain receives experience, toxin that interferes with normal pattern of development

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error of omission

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when developing brain fails to receive expected event or substance that is expected for normal pattern of development

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teratogen

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aspects of the environment that can cause serious harm to developing infant

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threshold effect

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when teratogen is virtually harmless until exposure reaches certain level

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synergism

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different environmental effects can act individually or in combination on the same developing system; risk associated with a given teratogen generally increases when combined with another teratogen or risk factor

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Wasting

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weight for height below 5th percentile; acute malnutrition

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Stunting

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height below 5th percentile; chronic malnutrition

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undernutrition

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inadequate nourishment and short stature; specific nutrient deficiencies

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marasmus

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insufficient calories; result in severe wasting of muscle and subcutaneous tissue

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kwashiorkor

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insufficient protein despite sufficient calories; edema and swollen potbelly

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LCPUFAs

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essential part of neural cell membranes and myelin

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Rickets

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deficiency or impaired metabolism of vitamin D; abnormal bone development

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Keratomalacia

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deficiency of vitamin A blindness corneal opacities

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preeclampsia

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high maternal blood pressure

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placenta previa

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placental low in uterus and partially or completely cover opening of cervix

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fetal fibronectin test

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measures presence of fetal fibronectin that binds fetal sac to uterus, negative is good

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cervical length

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effacement is thinning, dilation is opening

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tocolytics

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slow labor for 24-48 hours

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glucocorticosteroids

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steroid that crosses placental barrier and stimulates production of surfactant in lungs

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Respiratory distress syndrome

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due to lung immaturity and lack of surfactant results in lungs that collapse easily and take extra pressure to inflate; symptoms: rapid breathing, nasal flaring, poor coloring, grunting, rapid heart rate

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surfactant

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slippery protective substance in the alveoli of the lungs

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Bronchopulmonary dysplasia

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chronic lung inflammation and scarring due to prolonged oxygen exposure and mechanical ventilation

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retinopathy of prematurity

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abnormal development of retina due to oxygen exposure

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apnea/bradycardia

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breathing apnea or heart beat slows down, pauses or stops, related to immature lung and brain functioning

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IVH

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bleeding into ventricular system and surrounding tissue, toxic to brain matter,

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PVL

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restriction of blood supply, leading to white matter damage, can occur as focal injuries(cysts) or diffuse injury

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neonatal sepsis

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bacterial infection occurring within first 24 hours, caused by maternal infection; prolonged rupture of membranes, treated with antibiotics

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NEC

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death of intestinal tissue, bacterial infection; distended abdomen, treated with antibiotics and possibly surgery

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kernicterus

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brain damage due to high bilirubin