Reproduction and Development

The Cycle of Life You

Cancer  Disorder caused when cells lose the ability to control the cell cycle  Damaged cells replicate without control or fail to self-destruct when needed  Damaged cells form a tumor that invade healthy functioning tissue  Cells can metastasize (move to new areas of the body)

The Cell Cycle

Interphase

Interphase (cont)  Time of growth, normal activity, and preparation for division  ___- some cells enter this stage after birth; they perform normal processes but do not prepare for division; some cell enter for awhile, some for life  ___- time of growth and normal activities

Interphase (cont)  ___- replication of DNA, two copies of the same chromosome are now held together at a centromere; cell will prepare the protein that will form the spindle and prepare the centrioles  ___- time for growth and normal activities; extra cellular components are also made

Cell Division  Occurs in two stages Mitosis- division of the ________ Cytokinesis- division of ____________

Mitosis  Division in ________ cell  Divides one cell into two _________ __________ cells  Cells start ______ and end ______

DNA Review  Chromatin- Form of DNA during ________  Chromosome Form of DNA during cell division __________- center point holding two sister chromatids together Sister _________- two copies of a chromosome held together by a centromere

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cytokinesis

Controlling the Cell Cycle  Factors affecting mitotic rate ___________- cells stop growing as they crowd (outside) _________ and growth factors- chemical signals from outside cell (outside) Cyclins and kinases- chemical signal from inside cell (________)

Controlling the Cell Cycle (cont)  __________- tips of chromosomes with repeating DNA sequence (inside) Shortens every time mitosis occurs Cells only divide about 50 times before stopping division Some cells can divide more because telomerase repairs the telomeres

Controlling the Cell Cycle (cont)  Checkpoints (inside) DNA Damage Checkpoint (___)- halts division until damage can be repaired Apoptosis Checkpoint (___)- enough survivins must accumulate to push cell into division Spindle Assembly Checkpoint (_________)- halts mitosis if chromosomes are not properly attached to spindle

Cell Death- Apoptosis  Cell receives signal  Caspases destroy cell creating small pieces that can be phagocytized  Mitosis and apoptosis are used together to create structures and keep them healthy

Down Syndrome  Disorder caused by gametes that were made improperly during meiosis  Individuals receive an extra chromosome 21  The extra genetic material leads to the symptoms

Meiosis  Division to form __________  Creates four ______ cells  Cells start ______ but end _______  Occurs in ____ divisions Reduction division- cuts chromosome number in ______ Equational division- very similar to mitosis

Prophase I

Prometaphase I

Metaphase I

Anaphase I

Telophase I

Cytokinesis I

Meiosis II  Similar to _______  Two haploid cells created by Meiosis I both divide  Creates four haploid cells

Spermatogenesis  Spermatogomium stem cell divides (mitosis) to form one spermatogonium and one primary spermatocyte  Primary spermatocyte divided (meiosis I) to form two secondary spermatocytes  Both secondary spermatocytes divide (meiosis II) to form four spermatids  Spermatids mature into sperm

Oogenesis  Oogonium stem cell develops into primary oocyte  Primary oocyte divides (meiosis I) to form one large secondary oocyte and one small polar body  After fertilization, both divide (meiosis II) to form one zygote and three polar bodies

Sirenomelia

Pregnancy  Begins at fertilization in the ________________  Divided into trimesters  Gestation length- ___ weeks  First 8 weeks- ______  Remaining time- ____

Embryonic Development  Zygote goes through cleavage (rapid division) to form a morula and then a blastocyst  Blastocyst implants in uterus forming structures like placenta to communicate with mother  Neural tube develops  Organogenesis begins forming primitive organs

Fetal Development  Growth and maturation of structures formed during embryonic period  Usually ultrasound preformed at 20 weeks to look for abnormalities; sex can be determined at this time

Multiples  Dizygotic (________) twins- two eggs, two sperm, alike as siblings but share uterine environment  Monozygotic (_______) twins- one egg, one sperm, same DNA Different types depending on what supporting structures they share If separate late, twins may become conjoined

Birth Defects  Can be _________ or __________ controlled  Genetic birth defects can be passed to other generations  Teratogens (chemicals causing birth defects) are environmental  Some birth defects are apparent some are subtle

Teratogens  Thalidomide  Illegal drugs  Alcohol  Cigarettes  Vitamins (overdose)  Some drugs  Some viruses

The Critical Period  Structures are affected if the toxin or the gene is around during that structure’s critical period  The brain’s critical period lasts throughout pregnancy so many birth defects have an effect here

Cell Specialization  ≈ ____ different cell specializations  Beginning cells of embryo are totipotent (can give rise to ____ other cell types)  Later in development these early cells create stem cells which are pluripotent (may give rise to ____, but not all, cell types)

Stem Cells  Stem Cell Divisions Can divide into two ____________ Can divide to form one stem and one __________ cell Progenitor cells go to divide and specialize into mature cell types

Sources of Stem Cells  Embryonic Stem Cells (ES cells) Obtained from 5-day old embryos Create an embryo clone using somatic cell nuclear transfer Create an embryo clone using somatic cell nuclear transfer  Somatic Stem Cells Collect stem cells from umbilical cord blood Collect or stimulate stem cell in organs throughout the body

Aging  Systems seem to peak at about ___  Many dominant genetic disorders will occur  Other multifactorial disorders will occur as environmental factors accumulate