Ch2: Reproduction

Autosomal Cells

Diploid (2n)

Contain 2 copies of chromosomes (46)

Germ Cells

Haploid (n)

Contain 1 copy of chromosomes (23)

Cell Cycle

Eukaryotic cell replication

Cell Cycle Stages: Dividing Cells

G1, S, G2, M

Cell Cycle Stage: Non-Dividing Cells

G0

G0 Stage

Living and performing functions

No prep for division

Interphase

G1, S, G2

Longest part of cell cycle (90% of time)

DNA in uncondensed chromatin for RNA polymerase

G1 Stage: Presynthetic Gap

Create organelles for energy and protein production

Increase size

G1/S Checkpoint

Restriction point

Controlled by p53 protein

Check DNA quality

DNA damage arrests cell until repair

S Stage: DNA Synthesis

DNA replication into 2 sister chromatids bound at centromere (no change in ploidy)

G2 Stage: Postsynthetic Gap

Cell grows and replicates organelles

Check DNA for errors

G2/M Checkpoint

Controlled by p53 protein

Enough organelles and cytoplasm for 2 daughter cells

M Stage: Mitosis and Cytokinesis

1 somatic cell into 2 identical daughter cells

Prophase, metaphase, anaphase, telophase

Cytokinesis: Split cytoplasm and organelles

Cyclins and Cyclin-Dependent Kinases (CDK)

Different levels during cell cycle

Specific cyclins activate CDKs into cyclin-CDK complex to phosphorylate transcription factors

Transcription Factors

Promote gene transcription for next cell cycle stage

Cancer

Damaged cells undergo mitosis

Cancer Mutation: TP53

Gene producing p53

Cell cycle not stopped to repair damaged DNA

Rapid division of damaged cells

Cancer Mutation: Oncogenes

Mutated genes actively promoting cell division

Cancer Mutation: Tumour Suppressor Genes

Mutated genes losing ability to regulate/arrest cell cycle

Tumours

Accumulation of damaged cells

Metastasis

Cancerous cells spreading through bloodstream or lymphatic system

Prophase

Chromatin condense into chromosomes

Nuclear membrane and nucleoli disappear

Centrioles migrate to poles and form spindle apparatus/fibres (microtubules)

Microtubule asters anchor centrioles on cell membrane

Spindle fibres connect to chromosome kinetochores

Prophase: Centrosome

Microtubule organizing centre

Contain centrioles

Responsible for correct DNA division

Prophase: Kinetochore

Protein structures at centrosome

Attachment points for kinetochore fibers of spindle apparatus

Metaphase

Kinetochore fibres from chromosomes interact with spindle fibres from centrioles

Align chromosomes at metaphase (equatorial) plate

Anaphase

Centromeres and sister chromatids split

Chromatids pulled towards poles by shortening kinetochore fibers

Telophase

Spindle apparatus disappears

Nuclear membrane and nucleoli reform

Chromosomes uncoil

Cytokinesis

End of telophase

Separate cytoplasm and organelles for daughter cells

Finite Cell Division

20-50 for somatic cells

Meiosis

In gametocytes

Produce 4 nonidentical sex cells (gametes)

1 round of replication and 2 rounds of division

Meiosis 1: Reductional Division

Separate homologous chromosomes pairs (from opposite parental origin)

Produce haploid daughter cells

Meiosis 2: Equational Division

Separate sister chromatids

Produce haploid daughter cells

Prophase 1

Chromatin condense into chromosomes, spindle apparatus forms, nucleoli and nuclear membrane disappear

Synapsis occurs to form tetrad held together by synaptonemal complex proteins

Prophase 1: Synapsis

Homologous chromosomes intertwine

4 chromatids = tetrad

Prophase 1: Crossing Over

Homologous chromosomes breaking at chiasma contact point to exchange DNA

Single and double crossovers

Cause genetic recombination by unlinking linked genes to increase variety

Prophase 1: Gene Linkage

Tendency for genes to be inherited together

Further apart on chromosome = less likely inherit together, more likely to undergo crossing over

Prophase 1: Mendel’s Second Law

Independent assortment

Inheriting 1 allele has no effect on likelihood of inheriting alleles for other genes

Metaphase 1

Homologous pairs (tetrads) align on opposite sides of metaphase plate

Pairs attach to 1 spindle fibre by kinetochore

Anaphase 1

Homologous pairs separate and centromeres stay intact

Pairs pulled towards opposite poles

Anaphase 1: Mendel’s First Law

Segregation and disjunction

Paternal and maternal homologues are randomly distributed into daughter cells

Nondisjunction Disorders

Homologous chromosomes (anaphase 1) or sister chromatids (anaphase 2) do not separate

Gametes have too little or too many chromosome copies

Affect autosomal and sex chromosomes

Telophase 1

Nuclear membrane reform around chromosomes (2 sister chromatids joined at centromere)

Haploid cells

Cytokinesis and interkinesis

Telophase 1: Interkinesis

Short rest

Chromosomes partially uncoil

Meiosis 2

Similar to mitosis

Separate sister chromatids

Prophase 2

Nuclear envelope and nucleoli disappear, centrioles migrate to poles, spindle apparatus forms

Metaphase 2

Chromosomes line up on metaphase plate

Anaphase 2

Centromeres divide to separate sister chromatids

Chromatids pulled by spindle fibers to poles

Telophase 2

Nuclear membrane reforms

Cytokinesis

Meiosis 2 End Product

Up to 4 haploid daughter cells

Biological Sex

Determine by 23rd chromosome pair

XX: Female

XY: Male

X Chromosome

Carried by ova or sperm

Contain large amount of genetic info

Mutations cause sex/X-linked disorders

X Chromosome: Hemizygous

Males have 1 copy

Always express allele

X Chromosome: Homozygous or Heterozygous

Females

Can carry allele

Y Chromosome

Carried by sperm

Contain little genetic info

Y Chromosome: SRY

Sex-determining region Y

Code transcription factor initiating testis differentiation

Male Reproductive System: Sperm Passage

SEVEN UP

__**S**__eminiferous tubules

__**E**__pididymis

__**V**__as (ductus) deferens

__**E**__jaculatory duct

__**N**__OTHING

__**U**__rethra

__**P**__enis

Testes

Gonads

Contain seminiferous tubules and Leydig interstitial cells

Seminiferous Tubules

Coiled

Produce sperm

Seminiferous Tubules: Sertoli Cells

Nourish sperm

Leydig Interstitial Cells

Secrete testosterone and androgens

Scrotum

Contain testes

Hang below penis to control temp

Epididymis

Sperm flagella gain motility

Stored until ejaculation

Vas Deferens

Sperm travel through during ejaculation

Surrounding muscles raise and lower testes to control temp

Ejaculatory Duct

Receive sperm from vas deferens

2 ducts fuse to form urethra

Penis

Sperm carried through by urethra and exit body

Seminal Fluid: Seminal Vesicles

Fructose to nourish sperm

Alkaline fluid

Seminal Fluid: Prostate Gland

Alkaline fluid

Seminal Fluid: Bulbourethral (Cowper’s) Glands

Viscous fluid for clearing urine and lubrication

Semen

Sperm + seminal fluid

Spermatogenesis

Stem cells: Diploid spermatogonia

S Stage: Diploid primary spermatocytes

Meiosis 1: Haploid secondary spermatocytes

Meiosis 2: Haploid spermatids

Maturation: Haploid spermatozoa (4)

Sperm: Head

Genetic material

Acrosome cap to penetrate ovum

Sperm: Midpiece

Mitochondria

Generate ATP for swimming from fructose

Sperm: Flagellum

Motility

Female Reproductive System: Ova and Fetus Passage

Please Fill Ur Car with Vanities

__**P**__eritoneal sac

__**F**__allopian tube (oviduct)

__**U**__terus

FETUS

__**C**__ervix

__**V**__aginal canal

Ovaries

Gonads

Produce estrogen and progesterone

In pelvic cavity

Ovaries: Follicles

Multilayer sacs

Produce ova

Contain, nourish, and protect ova

Peritoneal Sac

1 egg/month enter during ovulation

Line abdominal cavity

Fallopian Tube/Oviduct

Cilia propel egg forward to uterus

Uterus

Muscular

Hold fetus

Cervix

Connect to vaginal canal

Vaginal Canal

Sperm deposit

Vulva

External female anatomy

Oogenesis

Stem Cell: Diploid oogonia

DNA Replication: Diploid primary oocytes

Menarche and Meiosis 1: Haploid secondary oocyte and polar body

Fertilization and Meiosis 2: Haploid mature ovum and polar body

Oogenesis: Oogonia

Develop during fetal development

Oogenesis: Primary Oocyte

Replicated DNA

Present at birth

Arrested in prophase 1 until menarche

Oogenesis: Secondary Oocyte

Arrested in metaphase 2 until fertilization

Oogenesis: Polar Bodies

Unequal cytokinesis

No functional gamete production

Oocyte Layers

Zona pellucida and corona radiata

Oocyte: Zona Pellucida

Surround oocyte

Acellular mixture of glycoproteins (protection) and compounds for sperm binding

Oocyte: Corona Radiata

Outside zona pellucida

Cell layer adhering to oocyte during ovulation

Sperm penetrate with acrosomal enzymes

Oogenesis: Mature Ovum

Large cell containing cytoplasm and organelles

Contributions to Zygote: Ovum

1/2 DNA

Cytoplasm

Organelles

RNA

Contributions to Zygote: Sperm

1/2 DNA

Zygote

Diploid

Form from haploid sperm pronuclei and ovum

Sexual Development: Before Puberty

Hypothalamus inhibit gonadotropin-releasing hormone (GnRH) release

Sexual Development: Puberty

Hypothalamus release GnRH

Stimulate anterior pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Trigger other sex hormone production

Male Sexual Development: Fetal Period

Y chromosome cause androgen production for male sexual differentiation

Male Sexual Development: Infancy and Childhood

Low androgen production

Male Sexual Development: Puberty

LH stimulate interstitial cells to increase testosterone production

FSH stimulate Sertoli cells for spermatogenesis

Testosterone

Develop and maintain male reproductive system and secondary sexual characteristics

Decrease with age

Negative feedback on hypothalamus and anterior pituitary