Mitosis and the Cell Cycle
Multifactorial inheritance & disease
Many diseases have a clear genetic component but are not the result
of single gene mutations or chromosome defects
These include congenital disorders (eg spina bifida, cleft lip, congenital
Darwin theory of evolution
THE FETAL PERIOD
Developmental stage from week 10 to birth
Differentiation and growth of tissues occurs.
Developmental changes vital to make organs and tissues functional.
Period of dramatic growth.
Fetus 8g at start of 3rd month but grows to ~3400g at bi
Meiosis and the Sexual Life Cycle
Meiosis and the sexual life cycle: five key concepts
1. Offspring acquire genes from parents by inheriting chromosomes
2. Meiosis and fertilization and alternate in sexual lifecycles
3. Meiosis reduces the number of chrom
FERTILIZATION AND IMPLANTATION
Occurs when male genetic material from a spermatozoon fuses with
In humans, sperm and ovum fuse in upper third of uterine tube.
Sperm are deposited near to cervix.
After 30-60 mins they arri
by the end of this lecture you should be able to:
explain the roles of hydrogen bonding base pairing. and
hydrophobic interactions in stabilising the double helical
structure of DNA
Explain supercoiling in prokaryotic DNA
EMBRYONIC DEVELOPMENT II
Ancestral Membrane Structures
Early vertebrate ancestors evolved in eggs:
1. Amnion. Liquid-filled sac, protects and buffers developing embryo.
2. Chorion. Functions as a vascularised gas exchange site, next to the
EMBRYONIC DEVELOPMENT 1
Embryo begins with implantation, ends when organs are nearly formed:
week 2 to week 9
Inner cell mass becomes a flat plate of cells = embryonic disc.
Disc consists of 2 cell layers:
1. upper layer = epiblast
A workable definition of ageing is a progressive functional decline, with
gradual deterioration of physiological function including a decrease in
Ageing is an intrinsic, inevitable, and irreversible age-related process of
loss of viabi