bio test RAHHH

D.3.14 Anatomy of the human male and female reproductive systems 

Viviparous: giving birth to live young

Oviparous: laying eggs

Female Reproductive System

• Ovaries:  Produce, store, and release eggs and make hormones (estrogen and progesterone)

• Oviducts: location where fertilization occurs: embryo moves from here to uterus 

• Uterus: help nourish the baby while its developing

• Endometrium:grows tissue layer to prepare uterus for implantation  (muscular organ)

• Cervix: allows sperm into uterus; serves as a physical and chemical barrier to infection (produces mucus) 

• Vagina: canal lined with mucus; allows for menstruation, intercourse, and childbirth

• Vulva: external female genitalia, acts as sensory tissue and protection of internal structures from infection 

Male Reproductive system 

• Scrotum: sac protecting the testes; keeps outside the body where temperature is lower 

• Testes: makes sperm and produces testosterone 

• Epididymis: storage location of sperm; sperm mature here before moving to vas deferens 

• Vas deferens: transports mature sperm to the urethra in preparation for ejaculation

• Seminal Vesicle: produces fluid high in fructose; provides nutrients for sperm; as well as other proteins, enzymes, and mucus for semen 

• Prostate gland: adds alkaline (base pH) fluid to the semen; neutralizes the acidic pH of vagina

• Urethra: moves urine and semen 

• Penis: penis penetrates vagina for ejaculation of semen near cervix 

C2.1.12 Intracellular receptors that affect gene expression

• Chemical Signaling: reception, transduction, and response 

  • Activation of specific receptors that trigger chemical events causing cells to change behavior in response 

  • Transmembrane receptors: are cell receptors on the outside of the cell surface

Intracellular receptors: are those found inside the cell 

• Signaling molecules have to be small and hydrophobic to cross the membrane lipid bilayer

• Steroid/ cholesterol/ lipid hormones (general) 

1. The hormones diffuses through cell membrane

2. Hormones bind to receptors within cytoplasm or nucleus forming hormone-receptor complex

3. hormone-receptor complex attaches to the DNA at a specific gene

4. hormone-receptor complex acts as a transcription factor; turning on transcription of DNA to RNA

5. mRNA translated into protein at ribosome

6. Protein has an effect on the cell

• Testosterone Response:DBNATPG

1. Testosterone diffuses through membrane of muscle cell

2. Testosterone binds to receptor forming a hormone-receptor complex

3. Hormone-receptor complex moves into the nucleus through nuclear pore, Hormone receptor complex attaches to DNA 

4. Hormone receptor complex acts as a transcription factor (DNA to RNA);   

5. mRNA translated into a Serum Response Factor protein 

6. The Serum Response Factor protein causes growth of muscle cells

• Estrogen is produced in small amounts by adrenal glands and testis

• Testosterone is produced in small amount by ovaries and adrenal glands

D3.1.13 Control of the developmental changes of puberty by gonadotropin- releasing hormone and steroid sex hormones 

• Puberty: sequence of developmental changes in transition from childhood to sexual maturity 

• GnRH (Gonadotropin- releasing hormone)

  • Triggered by a part of brain called the hypothalamus; secretes GnRH (peptide/ protein hormone)  which travels to the pituitary 

  • GnRH released from Hypothalamus cell binds to transmembrane receptors at Pituitary cells triggering signaling cascade. Pituitary cells activate synthesis and secretion of LH and FSH

  • FSH and LH travel through the bloodstream to the gonads; FSH and LH bind to transmembrane receptors ultimately leading to the effects of puberty

Puberty in Males

• FSH (Follicle stimulating hormone)

  • FSH travel from pituitary through the blood to testes; binds to transmembrane receptor on Sertoli cells (nurse cells); leads to activation and maintenance of spermatogenesis 

• LH (Luteinizing hormone)

  • LH travels from pituitary through the blood to testes; binds to transmembrane receptor on Leydig cells; leads to production of testosterone 

• Testerone (lipid hormones)

  • Steroid hormone released from Leydig cells; travels through blood to various target cells

  • Leads to:

    • Enlargement of penis and testes 

    • Deepening of the voice

    • Growth of facial and pubic hair

    • Increase in muscle size and strength 

    • Bone growth

    • Increased sex drive

Puberty in Females

• FSH (Follicle Stimulating Hormones)

  • FSH travels through the blood to the ovaries; binds to transmembrane receptor on Granulosa cells (secrete estrogen) in a follicle; leads to development of the follicle and the production of oestradiol 

• LH (Luteinizing hormone)

  • LH travels through the blood to the ovaries; binds to transmembrane receptor on cells in the follicle and corpus luteum; leads to ovulation, development of corpus luteum, production of 

progesterone 

• Estrogen 

  • Oestradiol is secreted from the ovaries; travel through the bloodstream to oestradiol receptors

  • Leads to:

    • Enlargement of vagina and uterus

    • Development of breasts

    • Beginning of menstrual cycles

    • Change in body shape and fat deposition 

• Progesterone 

  • During puberty, progesterone's primary function is in development of breasts  

D3.1.6 Fertilization in human

• Once released, egg and sperm will die unless they find each other

  • Sperm can live about 5 days within the female reproductive tract

  • After ovulation the egg can live for 12 to 24 hours

• External fertilization

  • Sea Urchins (Spawning) releasing both egg and sperm into water 

• Movement of Sperm

  • Sperm move through the cervix into the uterus and swims towards the egg within the oviduct

  • Sperm are able to direct their movement towards an egg using thermaxis and chemotaxis 

    • Thermatotaxis: sperm change their swimming direction according to a temperature gradient, swimming toward warmer temperature 

    • Chemotaxis: sperm move in response to chemical gradient; sperm plasma membranes have receptors that detect chemical released by the egg

• Acrosome Reaction

  • Sperm must move through the cells of the corona radiata around the egg

  • Corona cells secrete hormones that trigger acrosomal reaction in sperm; sperms head digests the zona pellucida of the egg

• Membrane Fusion 

  • Fertilization occurs with the fusion of the sperm plasma membrane with the egg plasma membrane; sperm enters the egg cell; sperm tail and mitochondria do not enter the egg

• Cortical Reaction

  • Zona pellucida hardens to prevent entry of more sperm; ensure egg is not fertilized by multiple sperm and that the zygote will have the correct number of chromosomes

    • Juno protein helps trigger the reaction

• Mitosis

  • 24 to 30 hours after fertilization for sperm and egg to find each other and break down plasma membranes 

  • Each release 23 chromosomes which participate in mitosis; zygote divides to an embryo 

D3.1.16 Development of a blastocyst and implantation in the endometrium 

• Zygote: fusion of egg and sperm

  • Divides by rapid mitosis to form an embryo composed of genetically identical cells 

• Embryo Development (oviduct)

  • Embryo divides to create a solid ball of cells called morula

  • Five days after fertilization the cells of morula begin to differentiate and morula changes in blastocyst 

    • Blastocyst is a hollow ball about 250 cells; inner mass will develop into the fetus (end of 8th week) and the outer layer of cells develop into amniotic sac and placenta 

• Implantation

  • Blastocyst hatches out of the zona pellucida

  • Seven days after fertilization, the blastocysts undergoes implantation embedding into the endometrium of uterine wall  

• Embryo Development 

  • Formation of most internal organs and external body structures

    • Day 16: Heart and major blood vessels

    • Day 20: Heart pumps fluids through blood vessels

    • Day 21: First red blood cells appear

    • Week 10: almost all organs besides brain and spinal cord

D3.1.18 Role of the placenta in fetal development inside the uterus 

Mammals

• Vertebrates, have hair, milk production in mammary glands, and three bones in the inner ear

  • Monotremes: egg-laying mammals (platypus + echidna)

  • Marsupials: give birth to underdeveloped offspring that climb into mother’s pouch to complete development (Kangaroos, koalas, opossums)

  • Placentals: mothers carry fetus in uterus where its nourished via the placenta (cat, rodents, humans); uterus supports growing fetus but its very energy demanding for the mother

• Placenta

  • Temporary organ that develops from the blastocyst shortly after implantation; placenta is connected to the fetus via the umbilical cord and to the mother at the uterus

  • Composed of a combination of fetal and maternal tissues 

• Placenta Structure

  • Fetal half: Blood from fetus arrives at the placenta via blood vessels in the umbilical cord; blood vessels branch into chorionic villi

    • Cell that line chorionic villi  separate the maternal from fetal blood creating a selectively permeable barrier between the fetal and maternal blood supplies

    • The branching structure increases surface area through which nutrient and waste can be exchanged between fetal and maternal blood 

  • Maternal half: blood from mother flow to and from the paces surrounding the villus

    • The nutrition and oxygen in the mother’s blood moves into the chorionic villi and into the fetal blood supply

    • Waste products and CO2 from fetus are passed from the fetal blood in the chorionic villi into the mother’s blood 

• Placenta Function

  • Endocrine organ, producing hormones that regulate both maternal and fetal physiology during pregnancy

    • Human Chorionic Gonadotropin: maintains the ovarian corpus luteum to ensure a new follicle does not mature and another egg is not ovulated; suppress mother’s immune system so the embryo is not rejected 

    • Oestradiol and progesterone: maintains the endometrium during pregnancy and stimulates mammary gland development 

• From mother to fetus (Umbilical vein)

  • Glucose, Amino acids, lipids, oxygen, water, antibodies, hormones, ions

• From Fetus to mother (Umbilical arteries)

  • Carbon dioxide, water, ions, Urea and other waste products 

• Placenta Transport -  Simple diffusion 

  • Simple diffusion: substance moves from higher to lower concentration directly through membrane; movement of gases (O2 and CO2).

    • O2 moves from maternal blood to fetal blood

    • CO2 move from fetus’s blood into maternal blood

• Placenta Transport- osmosis

  • Osmosis: movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration.

    • Can move directly through the cell membrane or aquaporins, which are integral membrane proteins that serve as channels in the transfer of water using facilitated diffusion

• Placenta Transport- facilitated diffusion

  • Facilitated diffusion: passive movement of molecules from high to lower concentration through a channel protein

    • Simple carbohydrates (glucose) are transported by facilitated diffusion from mother to fetus through Glucose transport channel proteins in the cells of the chorionic villi

      • Fetus has lower glucose levels, mother has higher levels

• Placenta Transport-active transport

  • Active transport: movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration; requires cellular energy (ATP) to power pump proteins

    • Amino acids (proteins): brought to fetus through active transport 

• Placenta Transport- bulk transport

  • Antibodies: proteins the immune system produces to help protect the body against infections

    • These are taken into the cells of chorionic villi by endocytosis; the cell uses vesicles to transport the antibodies to the opposite side where they are released into fetal blood by exocytosis. (ACTIVE)

D3.1.17 Pregnancy testing by detection of human chorionic gonadotropin secretion

• Human Chorionic Gonadotropin: hormones produced during pregnancy

  • Produced by outer ring of cells of the embryo and from the placenta 

• Function: 

  • Stimulate the corpus luteum and placenta to continue to produce progesterone; which maintains the endometrium of the uterus

• Pregnancy Tests

  • They use monoclonal antibodies to detect hCG, the monoclonal antibodies (Y) are proteins that are synthesized in a lab and are capable of binding to ONE specific target molecules 

  • Monoclonal antibodies bound to enzymes that trigger a color change 

1. Start:  A sample of urine is placed on the surface of the test strip; if the person is pregnant hCG is present. If they aren’t then hCG isn’t present.

2. Reaction zone: Urine sample moves to free antibody(Y) complementary to shape of hCG; if the hCG is present it will bind to the free antibody as the urine move

3.  Test zone: A different antibody (Y) is immobilized at the test window; if hCG is present in the sample it will bind to the antibody causing a color change and a line. No hCG no line

4. Control zone: contains different immobilized antibodies bind directly to antibody from step B (Y); if the test works the enzyme is activated and a line will appear for all samples; ensure test strip is functioning 

A2.3.1 Structural features common to viruses 

• Viruses are nonliving

  • Not made out of cells 

  • Can’t maintain homeostasis; can’t perform independent metabolism

  • Can't grow or replicate themselves 

• Viruses are obligate intracellular parasites

  • Strict molecular parasites of cells; must infect and reproduce inside them 

• Viruses are Very diverse

  • Viruses share few features suggesting they have multiple origins 

  • Vary in: Size, shape, genetic material, genes present, enveloping 

• Structures common to viruses (All viruses)

  • Use nucleic acid as their genetic material (RNA and DNA)

  • Have an outer coating (capsid) made of protein

A2.3.2 Lytic cells of viruses 

• Diversity of viruses capsids 

  • Capsid: protein shell of a virus that encloses its genetic material

  • Shapes: either helical or icosahedral; some complex architecture shapes 

• Same mission:

  • Hijack cellular machinery; find appropriate host cell

    • 1. Make more virus nucleic acids (DNA and RNA)

    • 2. Make more virus proteins

    • 3. Assemble new molecules

• Virus envelopes

  • Either enveloped or non-enveloped

  • Enveloped viruses: possess a lipid bilayer membrane on the outer part of the virus

    • Viral envelopes are acquired from host cell membrane during maturation of the virus called “budding”

  • Non-enveloped: absences of lipid bilayer membrane on the outer part of the virus

• Example virus

  • E Coli; double stranded linear DNA; icosahedral head to a  helical tail; non-enveloped; lytic and lysogenic life cycles ; no human disease

  • HIV: targets T cells; two copies of single stranded RNA (retrovirus); Icosahedral capsid with an envelope; RNA to DNA to make more copies; lytic life cycle

• Bacteriophage Lambda

  • Obligate intracellular viruses that infect bacteria; Lambda infects E. coli

  • Two approaches of infection:

    • Lysogenic cycle: virus assimilates its genome within the host cell’s genome to achieve replication without killing the host 

    • Lytic cycle: virus reproduces and bursts out of the host cell, killing it

      • 1. Phage attachment to host ell

      • 2. Phage DNA entry into host cell

      • 3. Phage DNA replication

      • 4. Phage protein synthesis

      • 5. Assembly of new phage virus 

      • 6. Lysis

      • 7. Spread