1
Q
What are the three germ layers in the embryo and what parts of the body do they give rise to?
A
- Endoderm: visceral organs
- Mesoderm: connective tissue and muscles (mesenchyme)
- Ectoderm: epidermis and neural tissue
2
Q
What are the seven types of connective tissue?
A
- muscle tissue
- nerve tissue
- bone/cartilage tissue
- hematopoietic cells
- vascular tissue
- fibrous tissue
- adipose tissue.
3
Q
What is the major cell of connective tissue and what is its function?
A
- Major cell is the fibroblast
- Function: synthesizes ECM/proteins (collagen/reticular fibers/elastic fibers)
4
Q
What are the two main subtypes of connective tissue?
- Name subtypes of these subytypes if any
A
Loose and Dense (Regular & Irregular)
5
Q
What is the purpose and location of loose connective tissue?
A
- Purpose - anchoring, support, source of cells
- Location:
- Underneath epithelium
- Site of initial attack by bacteria - but will be destroyed by immune cells (i.e. mammary gland, gut epithelium) → swelling/edema
6
Q
What is the composition of loose connective tissue?
A
- Composition
- Loosely arranged fibers that are irregular/disorganized
- Sparse collagen fibers
- Abundant ground substance
- Abundant cells (immune cells)
7
Q
What is the purpose and composition of regular dense connective tissue?
A
- Purpose - strength
- Composition
- Collagen fibers in parallel array and densely packed
8
Q
What are the three main locations of regular dense connective tissue fibers?
A
- Tendon (muscle to bone)
- Ligaments (bone to bone)
- Aponeuroses (muscle to muscle)
9
Q
What is the purpose and composition or irregular dense connective tissue fibers?
A
- Purpose - resists stretching and distension (skin dermis/colon)
- Composition
- Mostly collagen fibers that are irregular (random orientation)
- Sparse amounts of cells, mostly fibroblasts
10
Q
What is the purpose of the collagen fibers?
A
Allow for flexiblity with tensile strength
11
Q
What is the composition of collagen fibers and what is the hierarchy of the structure?
A
- Composition: procollagen (triple helix - 3 alpha chains) → collagen molecule (tropocollagen) → fibril → fibers
12
Q
Of reticular fibers, what is the:
- purpose
- location
- composition (what type of collagen)
- synthesizing cell
A
- Purpose: provide supportive framework for cells
- Location: supporting stroma in lymph nodes, spleen
- Composition: Type III Collagen fibers, mesh-like arrangement (like a cage)
- Synthesis: by fibroblast mostly
13
Q
Of elastic fibers, what is the:
- purpose
- location
- composition (what type of collagen)
- synthesizing cell(s)
A
- Purpose: allows tissue to stretch/distend, but return to original shape
- Location: major part of vertebral ligaments, elastic arteries, larynx)
- Composition: branching network
- Central core of elastin
- Surrounded by fibrillin microfibril - organizes elastin
- Random coiling → elasticity
- Synthesis: fibroblasts and smooth muscle cells
14
Q
What is the extracellular matrix?
What three things does it contain?
A
- Extracellular Matrix
- Network that supports and surrounds cells within connective tissue
- Contains: collagen, elastic fibers, ground substance (makes up a big component)
15
Q
What is the description and composition of ground substance?
A
- Description: watery substances that allow for the diffusion of oxygen/nutrients from vasculature to cells
- Composition:
- Proteoglycans
- Glycosaminoglycans (GAGs) attached to core protein
- Multi-adhesive glycoproteins - serve as attachment points within ground substance
16
Q
What are the two types of connective tissue cells?
A
- Resident Cell Population (permanent, non-migratory)
- Wandering and Transient Cell Population (predominantly cells from the blood)
17
Q
What are the 5 types of resident cell populations?
A
- Fibroblast – main cell of connective tissue; makes collagen etc.
- Macrophages (Tissue histiocyte) – phagocytic cell
- Adipose Cells
- Mast cells
- Undifferentiated Mesenchymal Cells
18
Q
What are the types of wandering and transient cell populations?
A
- Wandering and Transient Cell Population – predominantly cells from blood
- Lymphocytes
- Plasma Cells
- Neutrophils (PMN’s)
- Eosinophils
- Basophils
- Monocytes
19
Q
What are the types of collagenopathies (diseases of collagen)
A
- Osteogenesis Imperfecta
- Ehlers-Danlos Syndrome
20
Q
How does osteogenesis imperfecta occur and what is it a defect in (what subtype specifically)?
A
- Inheritable defect (most common autosomal dominant) of collagen Type I
- Defect in quantity AND quality of collagen
- Bone is most affected (90% of bone is Type I collagen)
- Mutations in genes that code for a-1 and a-2 chains of collagen molecules
21
Q
What are the symptoms associated with osteogenesis imperfecta?
A
- Soft, thin, brittle, deformed bones - because of ineffective bone formation
- Collagen forms abnormally (not parallel)
- Very prone to repeated fractures with ineffectual healing
- Blue sclera
22
Q
How does Ehlers-Danlos Syndrome occur and what is it a defect in (what subtype specifically)?
A
- Defect:
- Collagen Type III
- mutation in lysyl hydroxylase → abnormal cross-linking of collagen fibers
23
Q
What tissues are most affected in Ehlers-Danlos Syndrome?
A
- Tissues rich in collagen, such as skin and hollow organs (GI and blood vessels) are most affected
- Tissues lack tensile strength → hyperextensile skin, hypermobile joints
- joint dislocation
- Skin is stretchable, fragile, prone to trauma,
- Internal organs → rupture (GI, great vessels)
- Rupture of cornea and retinal detachment
- Tissues lack tensile strength → hyperextensile skin, hypermobile joints
24
Q
What are the two disorders of elastic fibers?
A
- Marfan’s Syndrome
- Solar Elastosis of Skin
25
Where does the defect lie in Marfan's Syndrome?
What function does this defect affect and where is this protein abundant in?
* Inherited defect in Fibrillin1 (glycoprotein)
* Fibrillin1 is the scaffolding upon which tropoelastin is deposited to form elastic fibers
* Particularly abundant in aorta, ligaments, and lens
* Aortic Rupture
26
What causes solar elastosis of the skin and where do the defects lie?
* Repeated exposure to ultraviolet radiation → premature aging (wrinkling, solar elastosis, irregular pigmentation)
* UV radiation → degradation of collagen and remodeling of fibrillin microfibrils → truncated → nonfunctional elastic fibers → decreased skin elasticity
* Seen as irregular fibers and bluish discoloration in dermis
27
How/Why does a keloid occur?
* Hypertrophic scar, due to excessive collagen accumulation in response to injury
* Does not regress on its own but extends beyond boundary of injury
28
What did Griffith's experiement achieve?
Dicovered the transformation of pathogenic pneumococcal S-bacteria strain to non-pathogenic R-bacteria to kill rats
29
What did Avery's experiement achieve?
Continuation of Griffith's experiment; Digestion of different macromolecule → proved DNA was the transforming principle
30
What did Watson and Crick's experiment achieve?
Discovered the basic DNA structure and base pairs
31
What does replication mean (in regards to DNA)?
Replication: transmission of likeness of DNA
32
What does information flow mean (in terms of DNA)?
* Information Flow: DNA provides means for production of all of the cell’s proteins
33
What is mutability (in terms of DNA)?
* Mutability: heritable changes in cellular properties
34
What part of DNA is considered the primary structure? What makes up each of these parts?
* Mononucleotide Structure
* Base – purines/pyrimidines
* i.e. Adenine
* Nucleoside – base + sugar (via N-glycosyl linkage)
* i.e. adenosine
* Nucleotides – base + sugar + phosphates
* i.e. AMP, ADP, ATP
* Polynucleotide Structure
* 3’ → 5’ phosphodiester bond between sugar and phosphate
35
What makes up the secondary structure of DNA and what are the basic characteristics of this?
* Helix is right handed
* Sugar-phosphate backbone
* A-T, C-G form inside of helix
36
What re the forces that keep the DNA double helix together?
* Weak Forces: hydrogen bonds, hydrophobic, and stacking energy
37
Define the minor and major groove of DNA.
* Major Groove: occurs where the backbones are far apart
* Minor Groove: occurs where the backbones are close together
38
* What is the conventional notation of DNA and how is it read?
* What is the RNA transcript and what would it read in relation to the coding strand?
* What is the DNA template strand and what would it read in relation to the coding strand?
* Conventional Notation
* Read 5’ to 3'
* Coding Strand
* Will be the strand similar to RNA transcript (opposite of template)
* ACTGTCGATGCTA
* RNA Transcript
* Homologous to Coding Strand, but U subbed for T
* ACUGUCGAUGCUA
* Template Strand
* TGACAGCTACGAT
* Strand read for RNA replication
39
# Define denaturation (melting) of the double helix and how it occurs.
* What else can cause denaturation?
* Denaturation (melting): double helix unravels and separates into single strands by breaking hydrogen bonds
* Each sequence of DNA has specific melting temperature Tm based on GC ratio
* Heat, low pH, low salt concentration
40
Define reannealing.
* Reannealing: bringing back complementary DNA strands into double helix
41
Define hybridization.
* Hybridization: annealing of polynucleotides from unique sources (think PCR primers)
42
Compare the primary structure of RNA to that of DNA (3 differences).
* Ribose (RNA) vs. deoxyribose (DNA)
* Single-stranded (RNA) vs. double-stranded (DNA)
* Uracil (RNA) vs. thyamine (DNA)
43
What is special about the primary structure and secondary structure of tRNA?
* Primary Structure: tRNA utilizes modified bases in its primary structure
* Secondary Structure: tRNA has 3 hairpin loops and stem structure
44
Compare the secondary structure of DNA to that of RNA.
* Fold-back (hairpin) structure (RNA) vs. double helix (DNA)
45
What are the chemical differences in hydrolysis of RNA compared to those of DNA?
* RNA is readily hydrolyzed in presence of high [OH-] at 2’-OH group
* DNA lacks –OH group and is not easily hydrolyzed into mononucleotides
46
What are nucleases and what subclass is involved with DNA/RNA?
* Nucleases: break polynucleotides into mononucleotides
* Phosphodiesterases – class of enzymes which catalyze hydrolysis of phosphodiester linkages
47
What are restriction endonucleases, how do they function, and what are they used for?
* Sequence-specific DNAses that cut in the middle of palindromic sites
* Forms sticky ends that allow for human DNA to be inserted into vector for recombinant technology
48
* What is the function of the DNA polymerases and at what side of the DNA strand do they work?
* How do they work?
* What do they require to work?
* DNA polymerases catalyze the addition of nucleotides at the 3’ end; matches incoming nucleotide to the template
* * 3’ hydroxyl group attacks alpha-phosphate of incoming nucleotide
* Require:
* Both template nucleotides and a RNA primers
49
What are the different type of DNA polymerases for mammals and what are their functions?
50
How often are mistakes made in DNA synthesis and how are they fixed?
* A mistake is made about once every billion bases
* DNA polymerases have 3’ to 5’ exonuclease activity (backwards) that can excise one wrong nucleotide and substitue the correct one.
51
What is the general description of Fragile X Syndrome and what three nucleotide segment repeats?
* Fragile X
* DNA polymerase slippage that causes trinucleotide repeat expansion
* Repeating nucleotides: CGG
52
* What occurs in the initiation step of DNA synthesis?
* Where does it occur?
* DNA sequence, called the origin
* Primase adds an RNA primer to the origin which is extended by DNA polymerase
53
How is the RNA primer disposed of in humans?
RNA primer is excised and cleaved by endonucleases
54
* Describe the leading strand and lagging strand in DNA synthesis and how many origins and primers they require?
* What are the fragments made by lagging strands called?
* Leading Strand: only requires one origin and primer
* Lagging Strand: requires multiple origins and primers (Okazaki fragments)
55
What is the function of the DNA ligase?
completes gaps between Okazaki fragments
56
What is the function of the helicase?
opens up double helix following topoisomerase
57
What is the function of the topoisomerases?
promotes unwinding by removing DNA supercoils
58
What is the function of single-stranded-binding proteins?
stabilizes the fragments and prevents binding
59
Which enzymes can change the topology (relaxed vs supercoiled) of DNA?
What are the two types of this enzyme and how do they work?
Topoisomerases
* Topoisomerase I
* Makes a temporary single-stranded break that allows relaxation of a superhelix
* Topoisomerase II
* Makes a temporary double-stranded break to pass around another portion of DNA
60
* What are toposiomerase inhibitors and what are they used as?
* What are the two examples? How do they work?
* Topoisomerase Inhibitors: supercoil accumulation can lead to apoptosis of the cell
* **Doxorubicin**: inhibits topoisomerase II, allowing superhelical turns to accumulate and signal apoptosis
* **Etoposide**: inhibits topoisomerase II by binding the enzyme-complex and trapping the complex in its cleavable state
61
How is biological information based down to progeny in humans?
22 pairs of homologous autosomes + 2 sex chromosomes
62
How are choromosome composed...
in the nucleus?
during metaphase?
* In the nucleus, the chromatic material is condensed into an indistinguishable mass
* During mitosis, chromosomes separate into chromatids, which make them easy to identify under the microscope
63
What stains are used to distinguish chromosomes?
Giemsa stains are used to fix mitotic chromosomes, creating a reproducible banding pattern
64
What is a karyotype?
Difference between p and q arms?
Karyotype - the visualization of chromosomes based on number, size, and shape
P - short arm
Q - long arm
65
How do karyotypes differ between species?
Karyotypes vary between closely related species, but all code for a similar amount of proteins (# of chromosomes are not proportional to amount of genetic info)
66
What is X-chromosome inactivation?
How does it occur?
One X chromosome is inactivated due to presence of two X chromosomes carrying the same info (XP is paternal and XM is maternal)
Inactivation occurs by Xist RNA, which create Barr bodies that condense randomly chosen chromosomes to heterochromatin thereby inactivating the gene
67
What is mosaicism?
Mosaic manifestation occurs when XP and XM are inactivated at random embryonic stages causing the appearance of different phenotypes in different areas
68
Describe origin of replications?
* Origin of replication ensures precise chromosomal reduplication in the S Phase of the cell cycle
* DNA deletions in certain regions upstream can cause inactivation of origin of replication
69
Descirbe centromeres.
What are kinetochores?
* Centromeres determine chromatid separation during cell division
* Kinetochores are located at centromeres and are where the microtubules attach
70
Describe teleomeres.
* Protect chromosomal ends from shortening during replication
* Is defined by the sequence: AGGGTT
* Telomeres shorten with each cell division, and too much shortening can block cell division
* Telomeres are replenished by telomerases in germ-line cells. They contain RNA-dependent DNA polymerase
* Telomerases are also found in cancer cells allow for indefinite cell division
71
Describe SNPs.
SNP (single nucleotide polymorphism): allow for distinguishing of homologous chromosomes (due to different nucleotides)
72
Stages of mitosis?
How does it work?
* Mitosis
* PMAT
* Occurs with homologous chromosomes and separates them
73
Stages of meiosis?
How does it work?
* PMAT x 2
* Occurs with chromatids, forms tetrads through synapsis and separates them into daughter cells
* Occurs only in gametogenesis
74
Define the key concepts in genetic analysis: gene, allele, phenotype, genotype.
* Gene: basic units of hereditary information that occupy a fixed position (locus) on the genome
* Allele: variant forms of a gene located at the same locus of a chromosome
* Genotype: the allelic forms of the genetic info (i.e. Bb, bb)
* Phenotype: the physical characteristic that is manifested by the genotype (i.e. black hair)
75
What are the types of genotypes?
* Heterozygous: one dominant allele and one recessive allele (i.e. Bb)
* Homozygous: either both dominant alleles or both recessive alleles (i.e. BB or bb)
76
Describe the role of meiosis in relation to allele segregation.
Alleles segregate during meiosis and new allelic combinations form in the zygote
77
Explain the law of segregation.
* Each gamete from each parent (4 total) contains an allele
* One gamete is chosen from each parent to produce an allelic genotype of the descending generation
78
How do different genotypes lead to differing phenotypes?
* Presence of a dominant allele (homozygous dominant or heterozygous dominant) produces a dominant phenotype
* Homozygous recessive produces a recessive phenotype
79
What are pedigrees?
How are they used?
* Circle indicates female, square indicates male
* Pedigrees can be used to deduce allele possibilities in descending generations
* Helps determine recessive, dominant, and x-linked mutations based on the individuals in each generation
80
Explain dominat negative mutations.
Dominant negative mutations: a loss of function dominant mutation that poses a negative effect on the wildtype
81
Explain reduced/incomplete penetrance.
Reduced/incomplete penetrance: individuals that do not express the trait even though they carry the allele (absence or presence)
82
Explain variable expressivitiy.
Variable expressivity: refers to a degree of expression rather than its absence or presence
83
Explain pleiotrophy.
Pleiotropy: a single genotype that affects multiple phenotypes (many body systems are usually affected)
84
Explain co-dominance.
Co-dominance: Alleles that are presented equally in heterozygous state or dominant state (i.e. blood groups)
85
Explain mitochrondrial inheritance.
How does it relate to heteroplasmy?
If a mother is affected with a mitochondrial mutation, all her children will inherit the mutation as well - only the maternal mitochondrial DNA is inherited
Heteroplasmy: Daughter cells inherit different versions of the genome (mutated vs normal). Mutations are caused only after mutated mitochondrial DNA accumulates
86
Explain both sex-linked linkages.
List some related diseases.
* Y-chromosome linkage:
* Affected males will pass mutations onto every single male son
* X-chromosome linkage:
* No male to male inheritance
* Carrier female has a 50% chance of passing gene to her children
* Daughters who receive the trait will be heterozygous
* Sons who receive the gene will hemizygous and will manifest the trait
* Diseases: Hemophilia, Duchenne’s, Fragile X
87
What type of tissue is the arrow pointing to?
Loose Connective
HINT:
abundant cells in layer and irregular pattern
88
What type of tissue is surrounding the black circle?
Loose Connective
\*Circle is the mammary gland.
HINT:
abundant cells in layer and irregular pattern
89
What type of tissue is depeicted in the image?
Dense Irregular Connective
## Footnote
HINT:
Fibers in irregular pattern
90
What type of tissue is depicted in the image?
Dense regular connective
## Footnote
HINT:
fibers in parrallel pattern
91
What type of fiber is depicted in the image below?
Reticular fiber
## Footnote
HINT:
mesh like structure.
92
Identify tissue fiber.
Elastic fibers
## Footnote
HINT:
long fibers look like slinky(s)
93
Identify this picture.
Ground substance.
HINT:
ITS BLUE MOFO
94
Identify this.
Cartilage matrix
## Footnote
HINT:
Little blue cells with two dots - classical sign of collgen - Caleb
95
Identify what is around the green circle.
Adipose
## Footnote
HINT:
white globs
SPM
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