Results for "fertilization"

Human Biology - Fertilization and Development

Breeding and Selection Breeding: the mating and production of offspring by animals. The activity of controlling the mating and production of offspring of animals Selection: the act of choosing something or someone from a group Geneus species of livestock European cattle- Bos taurus Zebu Cattle- Bos Indicus Swine- Sus Scrofa Sheep- Ovis Aries Horse- Equus Cabellus Goat- Capra Hircus Dog- Canis Familaris Cat- felis catus Principles of Breeding and Genetics Phenotype: the characteristic of an animal that can be seen or measured Genotype: the genetic makeup of an individual (DNA) Phenotype= Genotype + Environment Genotype= phenotype - Envoromet Selection: differently producing what one wants in a herd. Allowing only certain mating to occur. Inheritance: transmission of genes from parents to offsprings Basic Cell Information Chromosomes: in the nucleus and contains genetic material Gene: an active area in the chromosome that codes for trait DNA: complex molecule of the chromosomes which is the coding mechanism of inheritance Gametogenesis: Process that the gonads produce cells that become gametes(ova and sperm) Spermatogenesis: production of sperm Oogenesis: production of egg or ova Meiosis- special type of nuclear division in which germ cells contain one member of each chromosomes pair Fertilization: when an egg and sperm unite from embryo Each contributes one chromosome per pair to new life Homosygous: an individual whose genes for a particular trait are identical or alike Heterozygous: individual who possesses unlike genes for particular trait Dominant: a gene that overpowers and prevents the expression of its recessive allele when the two alleles are present in a heterozygous individual Recessive: a gene that its expression is masked by dominant allele Allele: gene occupying corresponding loci on homologus chromosomes that affect the same trait What traits should one select? Only traits that contribute to productive efficiency and consumer acceptance are of economic importance Ex: reproduction, growth(pre-weaning, post weaning) Basis of Selection Appearance Genetic abnormalities Estimate carcas merit Fit standard for herd Reproduction record Individuals records Progeny testing Pedigree family Factors affecting genetic progress Selection differential Heritability Genetic interval Accuracy of records Genetic correlation Number of traits in selection program Things to remember about traits Heritability: amount of the phenotypic expression of a trait that is transmitted to offspring (enviroments have big effect) (h2) Heterosis: the tendency of a crossbred individual to show qualities superior to those of both parents Generation interval The average age of the parents when offsprings are born The shorter the generation interval, the faster the genetic interval Selection Methods Tandem Selection: Selection for one trait at a time Least effective: mattes rapid gain in a single trait, but is slow to reach selection goal involving several traits Independant culling: establishes minimum culling levels for each trait makes SLOWER gain for each trait, but reaches goals faster. Most effective when few traits are involved. Selection Index: each animal is rated numerically by combining performance of several traits into a single index New Mexico Ram Test Selection Index Index=12 + 40 (ADG) + 30(CWF) + SL - 12 (DIA) - o.5 (VAR) All variables expressed as ratio of individual to the average ADG= average daily grain CWF= clean wool fibers SL= staple length DIA= Fiber diameter VAR= difference between dide and Britch Breeding Systems Purebred breeder: develop breeding stock that pocessess the highest predictability for transmitting the most desirable inheritance possible purebred animal: meets the requiramnets of a recognized breed and whose ancestors are registered in the herd book of that breed Breed: race or variety of livestock where the members are related by descent and are similar Purebred breeders may use: Linecrossing: crossing different lines or unrelated animals of the same breed, it is also used as outcrossing for outbreeding systems. It results in an increased heterozygosity and heterosis (offspring will not breed true). Heterosis: increase in production in the offspring over average of parents. Inbreeding: mating of related individuals( sires and dams share at least one ancestor) results in a increase of homozygosisty Inbreeding coefficient: measures of how inbred an animal is( the probability two genes of a pair in an individual will be homozygous because they are replicates of a single ancestor gene Coefficient ranges from 0-1. 0=no change, 1=absolute certenity Increase inbreeding usually detrimental to: reproductive performance, pre-weaning growth, post-weaning growth, increase susceptibility to environmental stress Commercial Producers: make use of available genetic material in a manner to maximize production or give most efficient, rapid and economical prodyction possible Systems used by commercial producers Species crossing- how many result in nonfertile offsprings Crossbreeding- mating animals of different established breeds and takes advantage of complementary and heterosis(hybrid vigor) oucrossing/ linerarcrossing- mating of unrelated animals of same breed Grading up- making purebred sires to commercial grade females and their female offspring for several generations Most common species crosses Jack to mare= mule Stallion to jennet= hinny Zebu to european cattle= brangus cattle American bison to cattle= buffalo Cross breeding system- designed to maximize hybrid vigor(heterosis) and produce replacement females throught the rotation of different sire breeds Terminal Static crossbreding system Produces replacement females throught the rotation while taking advantage of producing crossbred offspring Also know as “terminal crossbreeding system” Replacament females can be purchased from or produced in separate population Composiste breeding system Combines desirable traits of two or more breeds of cattle into one package Composition must be carefully planed in order to achieve genetic merit Utilizes hybrid vigor without crossbreeding Systems of mating Determied by: type of facilities, breeding schedule, method of heat detection, genetic program, market target hand/Stud mating Purebred breeders use to control breeding Females are kept apart from the males until desire time of breeding, Horse, Rabbit and Poultry advantages prevents overse of particule sire certainity of mating and to which Sire can increase conception rate by 5-10%. Disadvantages increases labor estrus detection becomes a seven-day a week job Pen mating Males and females coexist throught the breeding seasons or year rounds Used mostly by commercial breeders advantages Minimum labor Heat detection is the responsibility of the sire disadvantages Uncertainty of mating and date of conception Uncertainty of infertile sires and of un-bred females May overwork sires Artificial Insemination referred as AI Process by which semen from male is placed into the reproduction tract of the female using mechanical means rather than by natural source advantages Decrease spreed fo disease Increase number of offspring from superior male Identifies the fertility of sire Reduces number of sires needed Allows mating of small females to larger males Genetic diversity disadvantages Requires trained level of management Increases time and supervision of the female herd for estrus detection Sire training Semen handling and special breeding facilities More costly Embryo transfer Removal of early pregnancy embryos from a genetically superior female and placement of these embryos into reproduction tract of a suitable recipient for gestation and parturition Reproduction defined: process by which animals produce offsrpings for the purpose of continuing the species. The process of reproduction begins with copulation, which is the mating of a male and female of the species Sperm cells from the male are deposited in the female reproduction tract and try to unite with an egg cell When fertilization( a sperm cell and an egg cell units) occurs, an embryo begins The embryo attaches to the wall of the uterus where it is protected, recieves nourishment, and develops When the new offspring reaches the end of the gestation period, it is delivered from the female reproductive tract in a process called parturition

Fertilization

Receptivity, Fertilization, and Fetal Milestones - Exam 2

AVS 472 Exam 2 Review - Male Reproductive Anatomy + Fertilization Processes

Spermatozoa Transport and Fertilization in Females

biology 2.1Unit 2.1: Mitosis and Meiosis Introduction By the end of this section, you should be able to: Define a chromosome. Define DNA as the genetic material. Define genes. Describe the structure of chromosomes. Describe the components of DNA. Define mitosis and describe its stages. Define meiosis and describe its stages. Relate the events of meiosis to the formation of sex cells. Compare mitosis and meiosis. Chromosomes, Genes, and DNA Almost all the cells of your body—except for mature red blood cells—contain a nucleus, which acts as the control center of the cell. The nucleus holds all the information needed to make a new cell and, ultimately, a new individual. Inside the nucleus are chromosomes, thread-like structures that store genetic information passed from parents to offspring. Chromosomes are made up of DNA (deoxyribonucleic acid), a molecule that carries the instructions needed to make all the proteins in your body. Many of these proteins are enzymes, which control the production of other chemicals and affect everything about how your body functions. Each species has a specific number of chromosomes: Humans have 46 chromosomes (23 pairs). Tomatoes have 24 chromosomes (12 pairs). Elephants have 56 chromosomes (28 pairs). Half of your chromosomes come from your mother, and the other half from your father. These chromosomes are arranged in homologous pairs, meaning they contain matching sets of genes. A karyotype is a special photograph that arranges chromosomes into their pairs. In humans, 22 pairs of chromosomes are called autosomes, which control most body functions. The 23rd pair is the sex chromosomes, which determine whether you are male or female: Females have two X chromosomes (XX). Males have one X and one Y chromosome (XY). DNA Structure DNA is a long, twisted molecule shaped like a double helix (a spiraled ladder). Each strand of DNA is made up of smaller molecules called nucleotides, which consist of: A phosphate group A sugar (deoxyribose) A nitrogen base The four nitrogen bases in DNA are: Adenine (A) → Always pairs with Thymine (T) Cytosine (C) → Always pairs with Guanine (G) Genes are small segments of DNA that carry instructions for making proteins. The sequence of these bases acts like a biological code, directing the cell to create specific proteins. In 1953, James Watson and Francis Crick, using data from Rosalind Franklin’s X-ray photographs, discovered the double-helix structure of DNA. Their discovery led to a huge increase in genetic research, including the Human Genome Project, which mapped all human genes. Mitosis (Cell Division for Growth and Repair) All body cells (somatic cells) divide using mitosis, a type of cell division that creates two identical daughter cells. Mitosis is essential for: Growth (producing new cells). Tissue repair (replacing damaged or old cells). Asexual reproduction (producing offspring with identical DNA). Stages of Mitosis Interphase The cell prepares for division by copying its DNA. Chromosomes are not visible under a microscope. Prophase Chromosomes condense and become visible. The nuclear membrane breaks down. Metaphase Chromosomes line up in the center of the cell. Spindle fibers attach to each chromosome. Anaphase The spindle fibers pull the sister chromatids apart to opposite ends of the cell. Telophase A new nuclear membrane forms around each set of chromosomes. The cell is almost ready to split. Cytokinesis The cytoplasm divides, forming two identical daughter cells. Mitosis is constantly occurring in areas like your skin and bone marrow, where new cells are needed regularly. Meiosis (Cell Division for Reproduction) Unlike mitosis, meiosis occurs only in the reproductive organs (testes in males, ovaries in females) and produces gametes (sperm and egg cells). Gametes have half the number of chromosomes (haploid, n=23) so that when fertilization occurs, the new cell has the correct chromosome number (diploid, 2n=46). Stages of Meiosis Meiosis consists of two rounds of cell division, resulting in four non-identical cells. Meiosis I: Prophase I – Chromosomes pair up and exchange genetic material (crossing over). Metaphase I – Chromosome pairs line up in the center of the cell. Anaphase I – Chromosome pairs separate and move to opposite ends of the cell. Telophase I & Cytokinesis – The cell splits into two haploid daughter cells. Meiosis II (similar to mitosis): 5. Prophase II – Chromosomes condense again. 6. Metaphase II – Chromosomes line up in the center. 7. Anaphase II – Sister chromatids separate and move to opposite sides. 8. Telophase II & Cytokinesis – Four unique haploid gametes are formed. Each gamete is genetically different due to crossing over and random chromosome distribution. Mitosis vs. Meiosis: Key Differences Importance of Mitosis and Meiosis Mitosis ensures that cells grow, repair damage, and replace old cells. Meiosis allows genetic diversity, which is essential for evolution and survival. Summary Chromosomes carry genetic information in the form of DNA. Genes are sections of DNA that code for proteins. Mitosis produces two identical daughter cells for growth and repair. Meiosis creates four non-identical sex cells for reproduction. Mitosis ensures genetic stability, while meiosis introduces genetic diversity

Development Biology Lab - Gametogenesis and Fertilization

Fertilization

Fertilization

CHAPTER 7: FERTILIZATION

Fertilization

lesson 2: Fertilization and Early Embryonic Development

fertilization

U02 L03_ Fertilization (Human Phys, S25)

Let’s break this down! I’ll give you a study guide covering asexual reproduction, sexual reproduction (in humans and plants), and Mendelian genetics — then I’ll create a test for you. ⸻ Study Guide for Asexual Reproduction, Sexual Reproduction, and Mendelian Genetics ⸻ I. Asexual Reproduction • Definition: Involves a single parent, producing offspring genetically identical to the parent (clones). • Types of Asexual Reproduction: • Binary Fission: Simple cell division (e.g., bacteria). • Budding: New organism grows from a bud on the parent (e.g., yeast, hydra). • Fragmentation/Regeneration: Organism splits, and each part grows into a new organism (e.g., starfish). • Vegetative Propagation: New plants grow from parts of the parent plant (e.g., runners in strawberries). • Parthenogenesis: Offspring develop from unfertilized eggs (e.g., some lizards, insects). • Pros and Cons: • Pros: Fast, no need for a mate, energy-efficient. • Cons: No genetic variation, susceptible to environmental changes. ⸻ II. Sexual Reproduction (Humans & Plants) Humans: • Process: • Gametes (sperm and egg) produced by meiosis. • Fertilization forms a zygote (diploid cell). • Male Reproductive System: Testes, epididymis, vas deferens, prostate, urethra, penis. • Female Reproductive System: Ovaries, fallopian tubes, uterus, cervix, vagina. • Hormonal Regulation: • Male: Testosterone (sperm production, secondary characteristics). • Female: Estrogen & progesterone (menstrual cycle, pregnancy). Plants: • Process: Alternation of generations (sporophyte & gametophyte stages). • Pollination: Transfer of pollen to stigma. • Fertilization: Sperm (from pollen) fuses with egg in ovule. • Structures: Stamen (male), carpel/pistil (female). • Seed & Fruit Development: Fertilized ovules become seeds; ovary becomes fruit. ⸻ III. Mendelian Genetics • Gregor Mendel’s Experiments: Pea plants, discovered inheritance patterns. • Key Concepts: • Genes & Alleles: Genes determine traits, alleles are gene variants. • Dominant vs. Recessive Alleles: Dominant alleles mask recessive ones. • Homozygous vs. Heterozygous: Same alleles (AA or aa) vs. different alleles (Aa). • Laws of Inheritance: • Law of Segregation: Allele pairs separate during gamete formation. • Law of Independent Assortment: Genes for different traits sort independently. • Genetic Crosses: Punnett squares, monohybrid/dihybrid crosses. • Probability & Ratios: Phenotypic/genotypic ratios. • Non-Mendelian Inheritance: Incomplete dominance, codominance, multiple alleles, polygenic traits, sex-linked traits. ⸻ AP Biology Practice Test Total Questions: 30 (Multiple Choice) Section 1: Asexual Reproduction (6 questions) 1. Which form of asexual reproduction involves an organism splitting into two identical cells? a) Budding b) Fragmentation c) Binary fission d) Parthenogenesis 2. Which organism commonly reproduces through budding? a) Bacteria b) Starfish c) Hydra d) Fern 3. A disadvantage of asexual reproduction is: a) Slow reproduction rate b) High genetic diversity c) Vulnerability to environmental changes d) Requirement of a mate 4. Which plant structure is involved in vegetative propagation? a) Petal b) Stigma c) Runner d) Anther 5. Parthenogenesis involves: a) Fertilized eggs developing into offspring b) Unfertilized eggs developing into offspring c) Fusion of gametes d) Regeneration of lost body parts 6. What is the primary benefit of asexual reproduction in stable environments? a) Genetic variation b) Rapid population growth c) Evolutionary adaptability d) Reduced mutation rates ⸻ Section 2: Sexual Reproduction (8 questions) 7. In humans, fertilization typically occurs in the: a) Uterus b) Vagina c) Ovary d) Fallopian tube 8. The male gamete in plants is contained in the: a) Ovule b) Anther c) Pollen grain d) Stigma 9. Which hormone triggers ovulation? a) Testosterone b) Progesterone c) Luteinizing hormone (LH) d) Estrogen 10. The female gametophyte in flowering plants is the: a) Ovary b) Pollen tube c) Embryo sac d) Sepal 11. Which part of the male reproductive system produces sperm? a) Epididymis b) Vas deferens c) Testes d) Prostate gland 12. The process where pollen is transferred from anther to stigma is: a) Germination b) Pollination c) Fertilization d) Sporulation 13. What structure develops into a seed after fertilization in plants? a) Ovule b) Ovary c) Stamen d) Pistil 14. Which term describes the fusion of egg and sperm to form a zygote? a) Gametogenesis b) Meiosis c) Fertilization d) Pollination ⸻ Section 3: Mendelian Genetics (16 questions) 15. Who is considered the “Father of Genetics”? a) Charles Darwin b) Gregor Mendel c) Rosalind Franklin d) James Watson 16. The physical expression of a trait is called: a) Genotype b) Phenotype c) Allele d) Chromosome 17. An organism with the genotype Aa is: a) Homozygous dominant b) Homozygous recessive c) Heterozygous d) Diploid 18. A Punnett square shows: a) The process of DNA replication b) Possible genetic combinations of offspring c) Chromosome number in gametes d) Evolutionary relationships 19. The expected phenotypic ratio for a monohybrid cross is: a) 1:2:1 b) 9:3:3:1 c) 3:1 d) 4:0 20. Which of Mendel’s laws states that allele pairs separate during gamete formation? a) Law of Independent Assortment b) Law of Segregation c) Law of Dominance d) Law of Inheritance 21. Incomplete dominance results in: a) Blended traits b) Both traits expressed equally c) One trait completely masking another d) A 9:3:3:1 ratio 22. A cross between two heterozygous individuals (Aa x Aa) produces what genotypic ratio? a) 3:1 b) 1:2:1 c) 9:3:3:1 d) 2:2 23-30

L22: Fertilization and Sex Determination in Mammals

L21: Germ Cell Development and Fertilization Overview

Reproductive 5 - Uterine cycle, Fertilization, Implantation

fertilization