Male Reproductive System

Reproduction

• Reproduction is the process where organisms produce offspring, sexually or asexually
• Humans reproduce through sexual reproduction, requiring the participation of two parents

Male Reproductive System

• The male reproductive system serves three primary functions: male gamete production, gamete storage, and gamete transfer to the female
• In males, sex cells or gametes are called sperm
• Sperm cells are produced in the testes (or testicles), the male reproductive organs
• The testes are located in the scrotum, which maintains a temperature about 3°C cooler than the body to facilitate healthy sperm production
• Testes are where sperm is produced and testosterone is released, containing seminiferous tubules, epididymis, and parts of the vas deferens
• Seminiferous tubules are tightly coiled within the testes, producing and developing sperm cells
• The epididymis stores newly made sperm until they mature for reproduction, located in the scrotum with the testes
• The vas deferens connects the epididymis to the urethra, adding fluid from the seminal vesicle and prostate gland to the sperm
• The prostate gland secretes an alkaline liquid containing enzymes to protect sperm in the female reproductive system, forming semen
• The seminal vesicle secretes liquid rich in proteins, enzymes, sugar, and vitamins, providing energy to sperm cells
• The urethra allows both semen & urine to exit the body, connecting to the testes via the vas deferens and to the bladder
• Bulbourethal glands (Cowper's glands) are pea-sized glands that release pre-ejaculate fluid to lubricate and neutralize acidity in the urethra
• The penis, consisting of flesh tissue, swells due to increased blood pressure (erection); semen is released via ejaculation during intercourse

Female Reproductive System

• The female reproductive system has five primary functions: receiving male gametes, gamete production, gamete storage, fertilisation, and caring for the zygote/fetus until birth
• In females, sex cells are called ova or eggs
• Egg cells are produced in the ovaries, which are the female reproductive organs
• Ovaries are responsible for the production of female gametes (ova or eggs) and hormones like oestrogen and progesterone
• The fallopian tube connects the ovaries to the uterus, where fertilization occurs
• The vagina, a muscular canal, connects the vulva to the cervix, playing a crucial role in menstruation, sexual intercourse, and childbirth
• The uterus (womb) is where the fertilized egg (zygote) implants and develops into a fetus and then a baby
• The cervix connects the uterus to the vagina
• The urethra is a tube in front of the vagina that connects to the bladder
• The vulva is the external female genitalia
• The clitoris enables the woman to feel sexual pleasure

Sexual Intercourse

• Sexual intercourse is when sperm enters the female reproductive system, a male inserts his penis into the woman's vagina
• Millions of sperm are ejaculated; they travel through the cervix to the uterus and up to the fallopian tubes
• Fertilisation occurs when the sperm meets the egg in the fallopian tubes, attaching itself to the uterine wall
• The fertilised egg develops into a zygote, then an embryo, then a fetus, and finally a baby over approximately 9 months

Variation

• A gamete is a sex cell (sperm or ovum) containing half the genetic information needed to produce a new organism
• Male and female gametes fuse to form a zygote
• A zygote needs one male and one female gamete

Transferring Genetic Information

• Gametes pass traits from parents to offspring
• Gametes contain 23 chromosomes within its nucleus
• During fertilization, chromosomes from each parent join to create a zygote with 46 chromosomes (23 pairs)

Types of Variation

• Offspring are not identical to parents or siblings due to variation
• Processes causing variation: genetic recombination, independent assortment, and dominant/recessive traits
• Genetic recombination:
• Occurs during meiosis, where homologous chromosomes swap parts, known as ‘crossing over’
• This mixes genetic material and creates new combinations of alleles
• This ensures offspring will be genetically diverse
• Independent assortment:
• Also occurs during meiosis, where chromosomes are randomly distributed into gametes
• Each gamete gets a different combination of maternal and paternal chromosomes
• This increases variation, causing siblings (excluding identical twins) to differ
• Dominant and recessive traits:
• Individuals inherit two alleles for each gene, one from each parent
• Dominant alleles are expressed if one or two copies are present
• Recessive alleles are only expressed if both copies are recessive
• This determines how traits are expressed in offspring
• Heterochromia (different colored eyes) due to rare mutations or other circumstances

DNA (Deoxyribonucleic Acid)

• DNA carries all the genetic material for an organism and determines its traits, having a double-stranded helix structure
• DNA comprises bases: thymine (T), adenine (A), cytosine (C), and guanine (G)
• T pairs with A, and C pairs with G, such as "Apple Tree (A-T) and Car in the Garage (C-G)."
• Nucleotides are nucleotides are made of a phosphate, a sugar called deoxyribose, and a nitrogenous base (A, T, C, G)
• Nucleotides are monomers, forming polymers as a strand of DNA
• DNA has a double-helix structure, requiring two complete strands
• Adenines pair with Thymines, and Cytosines pair with Guanines

DNA Bases

• There are two kinds of bases : pyrimidines (Thymine and Cytosine) and purines (Adenine and guanine)
• Pyrimidines have one ring of carbon and nitrogen atoms
• Purines have two rings of carbon and nitrogen atoms
• Two-stranded DNA fit together because of the nitrogenous bases to hydrogen bonds
• Thymine attracts to Adenine and Cytosine attracts Guanine opposite each other in a zipper-like model
• Watson & Crick found the two strands of the DNA double helix are held together by hydrogen bonds between nitrogenous bases on opposite strands

RNA (Ribonucleic Acid)

• RNA works as a messenger, decoder, and regulator of genetic information, with roles in protein synthesis and gene expression
• mRNA is a messenger in cells sending information from DNA to ribosomes to produce protein, has a single-stranded helix structure
• RNA bases: adenine (A), uracil (U), cytosine (C), and guanine (G)
• Uracil replaces thymine, pairing with adenine, called Apple Under the tree (A-U) and Car in the Garage (C-G)
• Nucleotides in RNA contains a phosphate, a sugar and a nitrogenous base (A, T, C, G). The sugar used in nucleotides is called Deoxyribose.
• Nucleotides are a type of Monomer, a chain of monomers makes a ploymer
• With RNA's single-helix structure, one strand of RNA forms a complete strand
• Adenines pair with Uracils, and Cytosines pair with Guanines.

Genes

• Part of the DNA coding for a protein
• Genes carry instructions for making proteins crucial for growth, development, and bodily functions, determining traits via alleles like eye and hair color

Chromosomes

• Chromosomes are section of DNA, packaged with proteins called histones
• Humans have 46 chromosomes (23 from each parent).
• DNA is packaged into chromosomes with histones, positively charged proteins that adhere to negatively charged complexes
• Chromosomes enable accurate DNA copying, DNA isn't always in chromosome form
• When the DNA isn't dividing, it is wrapped around histones, not coiled into a chromosome

DNA Replication

• DNA must be replicated precisely to prevent diseases
• The helicase enzyme separates the DNA strands creating a replication fork
• Single-strand binding proteins prevent rejoining
• The enzyme primase adds RNA primers for building the new strands
• DNA polymerase adds nucleotides to the 3' end of the RNA primer
• The new DNA strand builds in the 5' to 3' direction
• RNA primers are removed and replaced with DNA nucleotides
• DNA ligase joins fragments of DNA (Okazaki fragments)

DNA Polymerase

• A key molecule that adds nucleotides to make a new complement strand

Mitosis

• Mitosis is a cell division producing two identical daughter cells, happening in 4 steps
• Mitosis repairs injuries and aids body growth, not gamete production
• Interphase happens before mitosis where DNA replicates
• Cell growth G1 stage
• DNA replication S stage
• Preparation for cell division G2 stage
• The stages of mitosis:
• Prophase: Chromosomes condense, the mitotic spindle forms, and the nucleus is still there.
• Metaphase: Chromosomes align and the nucleus dissolves, while microtubules connect to centromeres
• Anaphase: Chromatids separate from spindle and are pulled to opposite poles of the cell membrane
• Telophase: Two nuclei, each with membranes around two groups of chromosomes form
• The mitotic spindle breaks down

PMAT

• An easy phrase to help remember the order of the phases is PMAT (prophase, metaphase, anaphase, telophase)
• P for primary, M for middle (chromosomes line up in the middle of the cell), A for away (chromosomes are pulled away from the middle)and T for Two (chromosomes are on two opposite sides of the cell and have formed two new nuclei, each new nucleus has 46 chromosomes each).
• Cytokinesis occurs after mitosis, separating the cell with two nuclei, from the cytoplasm to be split

Cancer

• Uncontrolled, rapid cell mitosis

Meiosis

• It produces four haploid (half genetic, non-identical) daughter cells in eight steps
• Meiosis produces gametes with half the genetic information of the individual, not for body repair/growth
• interphase, DNA replicates
• Cell growth G1 stage
• DNA replication S stage
• Preparation for cell division G2 stage
• Meiosis I splits chromosome pairs (one from each parent) between two new cells, with each daughter cell having one chromosome with two chromatids
• Prophase I: Chromosomes pair, the nuclear envelope breaks down, and crossing over occurs, alleles swap
• Metaphase I: Homologous chromosomes line up, connected to centrosomes
• Anaphase I: Homologous chromosomes separate
• Telophase I: Chromosomes gather, and the nuclear envelope reforms
• Cytokinesis: the cell is separated into two daughter cells
• Meiosis II divides the cells into four daughter cells
• Chromosomes are not replicated, separating sister chromatids
• Prophase II: Chromosomes condense, and the mitotic spindle begins to form
• Metaphase II: Chromosomes meet in the centre, with centrioles attached to the centromeres
• Anaphase II: Each side of the chromosome moves to the opposite sides
• Telophase II: Chromatids arrange on each side of the cell. The nuclear envelope reforms
• Cytokinesis: The diploid cells becomes separated into two haploid daughter cells

Chromosomal Disorders

• Chromosome separation doesn't happened completely in Anaphase (I or II), the daughter cells end up with one less or one extra chromosome
• Down Syndrome is a chromosomal disorder, where the perso has an extra chromosome

Genes and Alleles

• Genes are a DNA sequence, carrying and particular instruction for the production of a polypeptide (gene expression)
• One or more polypeptides form proteins

Alleles

• Genes exists with alternate known as alleles, in the same position (locus) on the chromosome
• Alleles affects the expression of traits like eye colour (would be blue, or brown, or green eyes, etc.)
• Body cells contain two alleles for every gene, one from each parent

Dominant & Recessive Traits

• Allele is essentially, a gene is a codes for a certain trait
• Alleles are expressed differently
• Dominance express more than others
• Brown eyes are a more dominant allele whereas they express over the allele for blue eyes, therefore this is recessive

Alleles in Variation

• Alleles contribute to genetic diversity
• Individuals inherit alleles for each gene
• Crossing over contributes to variation

Genotypes & Phenotypes

• Genotypes are the alleles in the DNA
• Individual has two alleles
• Chromosomes show two alleles:
• Gene labelled A, is distinguished by uppercase eg. A, or a lowercase letter eg. a
• Chromosomes contains AA, one with Aa and one with aa
• A genetype shows the genes present, homozygous are the same and heterzygous are different
• AA (homozygous), AA (heterozygous), and az (homozygous). dominant trait is a a purple flower and the recessive trait is a white flower

Gregor Mendel

• Father of genetics, explaining variation between individuals

What Did Mendel Do?

• Austrian monk testing cross-pollinated pea plants, to understand that the traits displayed in parents show what traits display in patterns

Mendel's Laws

• the three fundamental laws of genetics:
• Law of Dominance and Uniformity - Each 'factor' (trait/gene) has two copies, inherited from each parent.
• Law of Segregation - Units seprate from each in the production of gametes
• Law of Random Assortment - Traits separate independently

Punnett Squares

• Punnett squares predict genetic outcomes using dominant(uppercase) and recessive letters(lowercase) to show inheriting alleles
• Parents on the X and Y axis
• Genotype is included, with some being Heterozygous and Homozygous recessive
• Phenotype has a chance or % that expresses the trait

Pedigree Charts

• Pedigree charts track traits through family trees, and symbolising for gender and expression Squares: male Circles: female Shaded shapes: has trait Unshaded shapes: doesn't have trait Half-Shaded: still have trait and carries it Lines connecting: vertical line to indicate generation, horizontal lines for relationships

Autosomal Traits

• Autosomal traits are controlled by autosomes (first 22 pairs)
• Dominant: Only one allele is required to express
• Recessive: Two alleles express the trait
• Person express disease from recessive alleles but with one allele is a carrier

Sex-Linked Traits

• Controlled by genes located on the sex chromosomes (X or Y).
• the X chromosome is larger
• Men have only one X chromosome
• Dominant and recessive letters are assigned separately

Heal the World

• Medical advances are achieved with biotechnology
• Genetic Engineering & CRISPR precisely edit genes to treat disorders, like sickle cell
• Stem Cell Therapy repairs tissues with regenerative medicine
• Personalised Medicine uses DNA sequencing for treatments
• Artificial Organs & Prosthetics created with 3D-printers and bionics

Feed the World

• Agricultural biotechnology
• Genetically Modified (GM) Crops for climate change
• Precision Agriculture with drones reduce waste
• Lab-Grown Meat reduces livestock farming

Save the World

• Environmental Protection, with biotechnology
• Bioremediation cleans oil spills with Microorganisms
• Conservation Genetics with DNA protects spiecies through breading
• Carbon Capture Technologies to absorb pollution with bacteria

Fuel & Clothe the World

• Biofuels (Ethanol, Biodiesel) reduce the use of fossil fuels
• Synthetic Biology creates biodegradable plastic
• textiles with GM cotton

Mutations

• Change in gene or chromosome that lead to genetic variation

Mutation Occurrences

• Mutations occur from internal factor such as issues and external factors from the environment
• Gene mutations alters genes, and changes traits
• Insertion - Inserting extra base
• Deletion - Remove a base from the DNA
• Substitution - Replace the base to a wrong one
• Chromosome mutations are mades genes, with duplicarion, deletion, inversion, and translocation

Mutation Effects

• Harmful mutations- Reduces chances of reproduction
• Helpful mutations - Increase chances of reproduction
• Neutral mutations - Doesn't alter anything

Evolution

• Darwin-Wallace Theory of Evolution
• traits, reproduce, and pass on their genes
• Population and evolution changes due to these factors: variation, inheritance, competition/selection

Natural Selection in Evolution

• Darwin-Wallace Theory has 3 conditions for evolution: Variation: change within a population Inheritance: Genes passed to offspring Competition/Selection: food limited

Natural Selection in Evolution

Peppered Moths – Moths survived the color soot on trees Antibiotic Resistance with bacteria survived with with stand to it.

Organisms Adapting Due to Evoloution

• natural selection can adapt survive with genetics and thrive for their traits, and change by reproduction
• white moths would have black dots to survived

Natural Selection Has Evoultion

• Fossil Evidence-
• Variety of Species
• Comparative Anatomy
• Genetics and DNA
• Embryology
• Biogeography
• Observed Evolution