Flashcards in Jones - reading Deck (45)
What is fitness?
Survivors selected by ability to reproduce
What is the gene pool constantly doing?
What is the purpose of reproduction?
Pass genes to next generation
How do most organisms reproduce?
How do unicellular organisms reproduce?
mitotically - produce two identical offspring
how do complex vertebrates reproduce?
Partenogenesis - egg cell doesn't need sperm to become an embryo
How do mammals reproduce?
what is produced at fertilisation?
what is the function of meiosis?
halves genetic material
produces germ cells
How do mammals increase genetic diversity?
exchanging pieces of homologous chromosomes
What is a mechanism of recognising fitness in mammals?
Negatives of sexual selection
Energy expenditure in finding, attracting and keeping a partner
exposure of both partners to death
Why do mammals reproduce by internal fertilisation?
Reduced number of eggs - energy expenditure
women undergo egg loss but mainly before egg growth
What is viviparity?
production of smaller eggs
development in vivo
birthing live young
Positives of viiparity?
reduces pressure to develop quickly
negatives of viviparity?
long gestation is demanding on females
there is a selective pressure on birthing as it can go wrong
How long do mammals display parental care for?
An extended period
What is fercundity?
How does fercundity differ in males and females?
Males - persists throughout life, slowly declines
Females - declines steeply at 35, ends at 50, due to loss of egg quality
Male contraception using testosterone levels
High testosterone leads to FSH stimulating spermatogenesis
could suppress endogenous testosterone production and therefore spermatogenesis
Shown as effective in some people - less in others
took a long time to get a low sperm count in some people
Male contraception using small molecule inhibitors of BRDT
BRDT= testes specific epigenetic reader protein
JQ1 = BRDT inhibitor - targets bromodomain and prevents recognition of acetylated H4
reduces sperm number and motility without altering hormones
reversible withing 1 month
Male contraception PLC3
Potential to inhibit PLC3 and prevent oocyte activation
no specific molecules found yet
female contraception Target the zona pellucida
immuniation of zona pellucida
this may cause abnormal cycles
Binding to the androgen and progesterone receptors
reduces testosterone conc in blood
effective and reversible
no serious side effects
disrupts spermatid adhesion to sertoli cells
premature spermiation - not mature enough to fertilise
Retinoic acid receptor antagonists
Aldehyde dehydrogenase in setoli cells synthesises retanoic acid
this is required for spermatageneis
Supress gonadorophins and sperm production
may be incomplete suppression
Nestorone and testosterone gel
blocks testosterone production and reduces sperm production
targets sertoli germ cell adhesion or sperm motility
Reversibly blocks vas deferens
prevents passage of sperm
impairs sperm function