REPRODUCTION IN HUMANS
Dr Adrian Mascia
Human Chromosomes
THE HUMAN GENOME
Each Human cell contains 46 chromosomes (2 pairs of the 23 types of chromosomes)
There are 22 types of autosomal (body trait) chromosomes
There are 1 pair of sex chromosomes (x or y)
Somatic cells:
Called Diploid Cells or 2N
have two sets of chromosomes = 46 in total
Humans have 23 homologous pairs of chromosomes in somatic cells
= 44 chromosomes + XX (females) or +XY (males)
THE HUMAN GENOME
Gametes (sex cells):
Have 23 chromosomes
Called Haploid cells or 1N
Sperm = 22 chromosomes + X or Y
Ova = 22 chromosomes + X
ANIMAL MITOSIS
MITOSIS SLOWMATION
WWW.CELLSALIVE.COM/MITOSIS.HTM
MITOSIS OVERVIEW
BEGIN: One cell containing 4 single stranded chromosomes
Anaphase:
Interphase:
Contraction of the miotic spindle, pulls toward the poles of the cells
Cell is in normal functioning state (replication of DNA material is
occurring)
Each centromere divides so that a single strand of DNA goes to
opposite sides of the cell
Cell spends most of its time in this state
(1 copy of each chromosome at each end of the cell)
Cannot see any chromosomes (unravelled)
Prophase:
Chromosomes begin to shorten and fatten (become visible) – true
beginning of mitosis
Centromere at centre of chromosome becomes visible
Telophase:
Clear division in chromosomal positioning, chromosomes become
thinner and less obvious
Nuclear membrane or cell wall begins to form around each group of
cells
Centrioles move apart, creating what is called a miotic spindle
CYTOKINESIS:
Metaphase:
Miotic spindle is formed
Double stranded chromosomes line up along equator of the cell (each
strand of chromosome called a chromatid)
Process by which cell membrane or wall encloses, separating the
genetic material, forming 2 cells
THE FEMALE REPRODUCTIVE
SYSTEM
Fallopian tube
Ovary
Uterus
Urinary bladder
Pubic bone
Urethra
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Cervix
Rectum
Vagina
THE MENSTRUAL CYCLE
• The menstrual cycle is controlled by internal feedback mechanisms between the
reproductive system and the endocrine system.
• The cycle takes an average of 28 days.
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THE MENSTRUAL CYCLE
Ovulation
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REPRODUCTION HORMONES IN HUMANS
Hormone
Produced by
Function
Testosterone
Testicles
Male sex traits
FSH
Pituitary
Stimulates egg/sperm
dvlp
Stimulate estrogen
LH
Pituitary
Stim. Testosterone
Release of egg, corpus
luteum, progesterone
Estrogen
Ovaries
Female sex traits
Progesterone
Corpus luteum
Maintains Uterus lining
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TYPES OF REPRODUCTION
Asexual vs. Sexual
PURPOSE OF REPRODUCTION
• To make sure a species can continue.
• Definition: Reproduction is the process by
which an organism produces others of its
same kind.
ASEXUAL REPRODUCTION
• A new organism (sometimes more than one) is produced from
one organism.
• The offspring will have hereditary material uniform with the
hereditary material of the parent organism. This means they will
be genetically alike.
TYPES OF ASEXUAL REPRODUCTION
• Budding
• Regeneration
• Fission (Binary fission)
BUDDING
• Process by which a new, duplicate plant or animal
begins to form at the side of the parent and enlarges
until an individual is created.
• Very common in plants;
http://www.waycross.edu/faculty/bmajdi/hydra%20budding.jpg
http://judyepstein.com/images/DesertImages/Budding-Purple-LG.jpg
REGENERATION
• The ability to restore lost or damaged tissues, organs
or limbs.
• It is a common feature in invertebrates, like worms and
starfish.
http://www.vsf.cape.com/~jdale/science/starfishregenerating.jpg
http://classes.design.ucla.edu/Spring05/152BC/projects/saito/ex3/planaria.jpg
FISSION
• Also called binary fission.
• Becoming two by division of the complete organism.
• A type of cell division.
http://wappingersschools.org/RCK/staff/teacherhp/johnson/visualvocab/BinaryFissionParamecium.jpg
http://coris.noaa.gov/glossary/binary_fission_186.jpg
SEXUAL REPRODUCTION
• Requires two sex cells – egg and sperm
• The egg and sperm join to form an entirely new
organism
• Different from the parent organism
IMPORTANT!
• Asexual reproduction results in offspring that are
genetically identical to the parent organism
• Sexual reproduction results in offspring that are
genetically different from the parent organisms