Abby Anderson Flashcards
(42 cards)
How do the bases of DNA nucleotides pair up, what type of bonding
Adenine (purine) pairs with thymine or uracil in RNA (pyrimidines)
Guanine (purine) pairs with cytosine (pyrimadine)
Pair via hydrogen bonds
What is the process of transcription
- Section of DNA containing gene unzips and unwinds under control of DNA helicase at start codon breaking H bonds
- The sense strand 5’-3’ contains code for protein
- Free RNA nucleotide bases pair with complementary bases on the antisense strand
- RNA polymerase forms phosphodiester bonds between RNA nucleotides
- Transcription stops at stop codon forming mRNA
- mRNA leaves through nuclear pore to ribosome as DNA helix reforms
What is the process of translation
- mRNA bonds to small subunit of ribosome at Start codon
- Complementary tRNA binds to start codon carrying the corresponding amino acid
- Next tRNA binds to next codon (max 2 tRNAs at once)
- First amino acid attaches to amino acid on second tRNA by peptide bond catalysed by peptidyl transferase
- Ribosome moves along mRNA to stop codon and polypeptide released
- May be modified further at golgi
What are autosomal traits
What are X linked traits
Genes present on non sex chromosome
A trait which gene is located on the X chromosome, diseases that are x linked usually affect males as they only have one allele of the gene
Explain monogenic inheritance
Inheritance of a trait through one gene with autosomal dominant traits being always expressed if present and autosomal recessive traits being expressed only if two copies of the allele are present
Explain polygenic inheritance
Define multi factorial traits
Give examples
Characteristics influenced by several genes showing continuous variation such as skin colour
Traits influenced by more than one gene plus environmental factors such as height
Define germ line mutation
Define somatic mutation
A mutation passed through gametes to the next generation so every cell in the new organism will carry the mutation
A mutation that occurs in a particular cell and cannot be passed on in reproduction
What is substitution mutation and what are the types of substitution mutation
What is deletion/insertion mutation and what can this lead to
When a single base or series of bases is swapped in the DNA code causing: Silent mutation Nonsense mutation Missence conservative Missense non conservative
Where a base is inserted or deleted into the DNA sequence, this can lead to frameshift mutation if not in multiples of 3
What happens in epigenetics
The structure of a base in DNA is modified but not changed to a new base, this can carry extra information which impacts how the code is expressed
What is the brocess of blastocyst formation (3 stages)
When does this occur
First week
On day 1: fertilization forming zygote
Day 2-3: diploid germ cell divides to form small bundle of cells called the morula
Day 3-4: morula develops into blastocyst consisting of the blastocyst cavity, inner cell mass and trophoblast (outer cell mass)
What characteristic do the cells of the blastocyst have
They are pluripotent- having the ability to develop into all tissue types in response to specific enviromental stimuli but not whole organism
What causes down syndrome
Caused by extra chromosome 21 in 95% of cases
When does the bilaminar germ disk develop
What is the process of bilaminar germ disc formation
Second week
Day 9: blastocyst develops into bilaminar germ disc as the inner cell mass divides into two layers, the epiblast and the hypoblast, the amniotic cavity develops inside the epiblast
When does gastrulation occur
What happens during gastrulation
Third week
The epiblast gives rise to 3 embryo layers under the control of locally acting cytokine growth factors
Mesoderm
Ectoderm
Endoderm
What is the process of gastrulation (3 stages)
- Cells from epiblast proliferate downwards from primitive streak and migrate laterally to form mesoderm between epiblast and hypoblast
- After proliferation epiblasts form ectoderm
- Once mesoderm comes into contact with hypoblast cells closest to hypoblast differentiate into cells of the endoderm
When does notocord formation occur
What is the notocord
What is the process of notocord formation
Third week
Notocord: rod shaped mesenchymal structure which defines the long axis of the embryo eventually to be replaced by vertebral column
Day 16-17: cells invaginating from primitive streak migrate cranially in midline between epiblast and hypoblast to give mesoderm layer, cells in the midline form the notocord
When does neural crest formation occur?
What is the process of neural crest formation? ( 4 points)
Third week
Day 19 onwards:
- notocord sends signals to endoderm causing neural plate to form and infold forming neural folds and groove
- this causes changes in crest of neural folds so some of the endoderm cells become neural crest cells
- neural folds fuse to form neural tube and neural crest cells become a distinct population
- neural crest cells migrate throughout the body
What causes spinal bifida and what does it result in?
Incomplete closure of embryonic neural tube
Leading to some vertibrae overlying the spinal cord after not forming fully and remaining unfused and open
How do neutrophils reach the infected area
Extravasion:
Rolling, integrin activation by chemokine, stable adhesion, migration through epithelium
What is the process of phagocytosis
4
- Microbe binds to receptor on phagocyte
- Phagocyte engulfs microbe creating phagosome
- Phagosome fuses with lysosome forming phagolysosome
- Microbe destroyed by lytic enzymes
What substances do NK cells use to destroy infected cells
What cells do NK cells target
Perforin and granzyme
Cells that have lost their class 1 MHC molecules
What is the compliment pathway
Pathway activated by classical pathway (antibody)/ alternative pathway(microbe) / lectin pathway (mannose binding lectin)
C3 splits into C3a (inflammation) and C3b (opsonisation and phagocytosis)
This triggers C5 to split into C5a (inflammation) and C5b
Proteins of complement cascade form MAC causing lysis of microbe
What are some innate immune components of the oral mucosa
5
Toll like receptors SLgA B defensins Mucous coat Intra epithelial lymphocytes
What are some innate immune components of the nasopharynx and tonsils
2
SLgA
B cells
