03 Special Topics

This deck of flashcards is for content about the third topic for BIOSCI107

where does fertilisation occur?

in the ampulla of the uterine tube

what is the result of fertilisation?

formation of a diploid zygote with a unique genome

how is polyspermy prevented?

through fast and slow block mechanisms to ensure only one sperm fertilises the egg

what is cleavage in early human development?

a series of rapid cell divisions that follow fertilisation, leading to the formation of the blastocyst

what are the resulting cells of cleavage called?

blastomeres

what structure forms after about 16-32 blastomere?

the morula, a solid ball of cells that eventually develops into the blastocyst

what is a blastocyst?

a hollow ball of cells with a fluid-filled cavity called the blastocoel

what are the two cell type sin a blastocyst?

trophoblast (outer layer) and inner cell mass (embryoblast)

what does the trophoblast become?

part of the placenta

what does the inner cell mass become?

the embryo

when and where does implantation occur?

around day 6 to 7 post-fertilisation, in the endometrium of the uterus

what does the trophoblast differentiate into during implantation?

cytotrophoblast and syncytiotrophoblast

what is the role of the syncytiotrophoblast?

invades the uterine wall and facilitates nutrient exchange and secretes hCG

what is gastrulation?

the process by which the three primary germ layers form from the epiblast

what structure is key in initiating gastrulation?

the primitive streak

what germ layer gives rise to the skin and nervous system?

ectoderm

what does the mesoderm form?

muscles, bones, cardiovascular system, kidneys, and reproductive organs

what does the endoderm form?

lining of the gastrointestinal and respiratory tracts, liver, and pancreas

what is the purpose of embryonic folding?

converts the flat trilaminar disc into a 3D embryo

what are the two main types of folding?

lateral and cephalocaudal folding

what major cavity is enclosed due to folding?

the body cavity (coelom)

what are some derivatives of ectoderm?

epidermis, brain, spinal cord, peripheral nerves

what are some derivatives of mesoderm?

skeletal system, muscles, heart, blood vessels, and kidneys

what are some derivatives of endoderm?

epithelial lining of digestive and respiratory tracts, liver, and pancreas

what is a totipotent stem cell?

can form all cell types, including the entire embryo and placenta

what is a pluripotent stem cell?

can form any cell of the embryo, but not extra-embryonic tissues

what is a multipotent stem cell?

can form several related cell types

what is a unipotent stem cell?

can produce only one cell type, but can still self-renew

why are stem cells useful in research?

they can differentiate into various cell types, making them valuable for studying development, disease, and regenerative medicine

what are induced pluripotent stem cells?

adult cells reprogrammed to become pluripotent and is used to model disease or test drugs

what ethical issues are associated with stem cell research?

the use of embryonic stem cells, which involves destruction of embryos

what are proteins made of?

amino acids linked by peptide bonds formed via dehydration reactions

how many different amino acids are there in proteins?

20, each with a unique R-group that affects folding and function

what do peptide bonds connect?

the carboxyl group of one amino acid to the amino group of another

what do the N-terminus and C-terminus refer to in a protein?

The start and end of the amino acid chain

what are the four levels of protein structure?

primary (amino aid sequence), secondary (local folding like alpha-helices and beta-sheets), tertiary (3D shape), and quaternary (multi-subunit association)

what stabilises secondary protein structure?

hydrogen bonds between backbone atoms in the polypeptide chain

what stabilises tertiary structure?

interactions between R-groups, including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.

what is quaternary structure?

the association of two or more polypeptide chains into a functional protein complex

what is the hydrophobic effect in protein folding?

non-polar side chains are buried inside the protein to avoid water

what factors can denature proteins?

changes in pH, temperature, and salt concentration

what is denaturation?

loss of protein’s 3D structure and function, often leading to aggregation

are proteins highly stable?

no, proteins are marginally stable and sensitive to environmental changes

what are globular proteins?

compact, usually soluble proteins with many functions

what are fibrous proteins?

elongated shapes, usually insoluble and provides support

what structural feature is common in fibrous proteins?

repetitive amino acid sequences forming alpha-helices or beta-sheets

give examples of globular proteins and their functions

collagen (connective tissue strength), and actin (cell structure and movement)

why is protein shape important in biology?

a protein’s 3D shape determines its function and interactions with other molecules

how is protein shape used in drug development?

drugs are designed to fit specific protein conformations, especially active or binding sites

what are common methods to determine protein structure?

X-ray crystallography, NMR spectroscopy, and cryo-electron microscopy

what is the Protein Data Bank (PDB)

a database of experimentally determined 3D protein structures

what is structure-based drug design?

designing molecules that bind and inhibit proteins based on their structural shape

what reaction is catalysed by malic enzymes?

conversion of L-malate to pyruvate with NAD(P)+ reduction

what is ME2?

A tetrameric malic enzyme involved in metabolic pathways

what is NPD-389?

a potent inhibitor of ME2 that reduces viability in breast cancer cells