HUB Paper 1 Flashcards
Chiasmata
Point where chromosomes are joined together in prophase 1
Independent Assortment
Random aligning of chromosomes in Metaphase
Spermatogonia
Dormant germ cells divide by mitosis to produce spermatogonia.
Primary Spermatocyte
Spermatogonia in Prophase I
Spermatids
Results of meiosis of primary spermatocytes
Acrosomal cap
Hydrolytic enzymes in head of sperm
Oogonia
Result of mitotic division of dormant germ cells in ovary
Primordial follicle
Oocyte surrounded by single layer of flattened cells (pauses in Prophase I)
Primary follicle
When follicle cells around primordial follicle plump up
Zona Pelucida
Glycoprotein layer around primary follicle
Antrum
Fluid filled cavity in a Graafian follicle
Ovulation
Follicle wall thins, ruptures, and oocyte slowly descends into the Fallopian tube
Corpus Luteum
Remaining ovarian follicle wall that is connected to ovary wall after ovulation
Sperm capacitation
Cholesterol from semen removed from aperm head, making it more permeable to calcium and increasing motility and facilitates release of enzymes from acrosomal cap
Integrins
Membrane proteins on oocyte that mediate attachment and penetration of sperm to oocyte plasma membrane
Fertlins and Cyritestins
Membrane proteins on sperm that mediate attachment and penetration of sperm to oocyte plasma membrane
Polyspermy
When more than 1 sperm enter the oocyte
Zygote
When pronuclei from egg and sperm in embryo fuse
Holoblastic cleavage
Complete cleavage
Meroblastic cleavage
Incomplete cleavage (too much yolk)
Blastocyst
After morula stage, has distinct ICM and TB
Morula
When blastomeres start to compact at 8-cell stage
Inner Cell Mass (ICM)
small group of cells on inside of blastocyst - gives rise to embryo
Trophoblast (TB)
Large group of external cells of blastocyst - gives rise to extra-embryonic tissue
Totipotent
Can give rise to anything
Pluripotent
Can give rise to lots but not all
Multipotent
Can give rise to a bunch, but less than pluripotent (blastocyst)
Monozygotic twins
2-cell embryo divides forming 2 embryos
Conjoined twins
When ICM doesn’t completely divide in monozygotic twins
Hatching
Embryo sheds Zona Pelucida in uterus to prepare for implantation
Implantation
Attachment of embryo to endometrium
Epiblast
Epithelial layer of ICM - becomes embryo and amnion
Hypoblast
Epithelial layer of ICM - gives rise to primary yolk sac
Extraembryonic Mesoderm (EM)
Populates space below TB
Gastrulation
Formation of 3 primary germ layers
Epiboly
Specialised form of gastrulation in organisms with ball-shaped embryo
Ectoderm
Outer germ layer
Mesoderm
Middle germ layer (connective tissue )
Endoderm
Inner germ layer (GIT)
Neural Induction
Formation of neural plate from thickening columnar cells above the notochord
Neurulation
Formation of neural tube from neural plate
Neural crest
Tips of neural groove
Eukaryotes
Nucleus, membrane-bound organelles
Prokaryotes
No nucleus, no membrane-bound organelles
Microvilli
Tiny finger-like projections of cell membrane containing microfilaments
Cilia
Hair-like structures on surface of cell containing microtubules
Flagella
Similar in structure to cilia but much longer
Cytoplasm
Area between plasma membrane and nuclear membrane
Microfilaments
- Smallest filament of cytoskeleton
- Actin & Myosin
Intermediate filaments
Exceptionaly strong filaments of cytoskeleton