General Biology 2 Notes PDF

GENERAL BIOLOGY 2​ ℅ Shanjay Aberin Plant Reproduction Flowers: The reproductive shoot of the angiosperms (Flowering plants) Receptacle: part of the stem where floral organs are attached Plant Reproduc...

GENERAL BIOLOGY 2​ ℅ Shanjay Aberin Plant Reproduction Flowers: The reproductive shoot of the angiosperms (Flowering plants) Receptacle: part of the stem where floral organs are attached Plant Reproductive Organs Sterile: ➔​ Sepals >> This encloses and protects the flower bud before it opens, Green and more leaflike ➔​ Petals >> Brightly colored than sepals and attract the flower to insects and other LIVING pollinators​ Male (STAMEN): ➔​ Anther - Produces Pollen, Contains Pollen Sacks ➔​ Filament - Long Neck Of The Anther Female (PISTIL / CARPEL): PISTIL - a single carpel or a group of fused carpels ➔​ Ovary - Contains Ovules ➔​ Ovules - Full Of Eggs ➔​ Style - Connects Stigma To Ovary ➔​ Stigma - Sticky, pollen sticks to it Reproductive Variation COMPLETE VS. INCOMPLETE FLOWER ➔​ Monoecious - Complete Flower ➔​ Diocesious - Incomplete ◆​ Gynoecious >> ONLY FEMALE; only OVULES ◆​ Dioecious >> Can be FEMALE or MALE BISEXUAL VS. UNISEXUAL FLOWER ➔​ BISEXUAL: Both Male and Female Parts of a Flower ➔​ UNISEXUAL: Only either Male or Female, NOT BOTH ◆​ STAMINATE - Male Parts ◆​ PISTILLATE - Female Parts 1  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin Asexual Reproduction VEGETATIVE PROPAGATION Asexual reproduction where the vegetative part of the plant gives rise to a new plant. A plant part falls from the parent plant and becomes a new plant SPORE FORMATION Applicable form of reproduction applicable to ferns. Once the spores are matured, they will disperse and grow in the environment. -​ Spore - single cell surrounded by thick cell wall for protection Steps of Sexual Reproduction 1.​ POLLINATION - Pollen gets picked up by pollinator (Insect, bird, win, etc.) and then gets dropped into the pistil of another flower 2.​ FERTILIZATION - Once the pollen enters the pistil and reaches the ovary, the ovary becomes fertilized 3.​ SEED FORMATION - From the ovule, it becomes a seed. The ovary becomes the fruit; if there is no fruit, the ovary becomes a seed. Alteration of Generations All plants go through a cycle between being sporophyte and gametophyte. ➔​ SPOROPHYTE - Asexual way of reproduction in plants, producing spores ➔​ GAMETOPHYTE - Sexual way of reproduction in plants, producing gametes Animal Development Early Development 1.​ The Zygote a.​ A fertilized egg that has the potential to produce all the diverse cell types of the complete individual b.​ In most vertebrate zygotes, the cytoplasm contains yolks which serve as the food for the developing embryo c.​ Human Zygotes don’t have yolks​ 2.​ Cleavage: From One Cell to Many a.​ Process wherein zygote undergoes RAPID MITOSIS (2 identical diploid daughter cells) b.​ Rapid cell division without growth 2  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin c.​ By about 24 hours after fertilization, the human zygote has completed the first mitotic division and reached the two-cell stage d.​ 16-CELL STAGE i.​ The embryo consists of a tiny cluster of cells called the MORULA ii.​ As cleavage takes place the embryo is pushed against the Uterine tube by ciliary (Cilia) action and muscular contraction iii.​ By the time that the embryo reaches the uterus, on about the 5th day, it is in the morula stage ​ 3.​ The Blastocyst a.​ Cells arrange themselves into hollow balls called blastocysts (Blastula), which form after the cleavage b.​ Eventually forming the nutritive membranes the chorion and placenta that surround the embryo c.​ A little cluster of cells, the inner cell mass, projects into the cavity of the blastocyst and produces the embryo itself​ 4.​ Implantation a.​ Implantation of the embryo in the endometrium (lining) of the uterus, begins on the seventh day of embryonic development b.​ During this period enzymes destroy some tiny maternal capillaries in the wall of the uterus, to temporarily provide a rich source of nutrition c.​ Implantation is completed by the ninth day of development​ 5.​ Formation of Germ Layers (Gastrulation) a.​ The inner cell mass of the blastocyst arranges itself to form a two-layered disk b.​ The cells of the lower level then merge to line an inner cavity, the primitive gut, or archenteron, which will eventually develop into the digestive tract and certain other structures c.​ These cells make up the endoderm, while the cells that remain cover the embryo and become its outermost layer from the ectoderm d.​ A third layer of cells the mesoderm proliferates (rapidly multiplies) between the ectoderm and endoderm e.​ Ectoderm, mesoderm, and endoderm are known as the three germ layers or embryonic tissue layers, each gives rise to specific structures in all vertebrate embryos​ i.​ Ectoderm 1.​ Nervous System 2.​ The outer layer of the Skin (epidermis) and its associated structures (Hair, nails, etc.) 3.​ Pituitary gland​ 3  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ii.​ Mesoderm 1.​ Skeleton (Bone and Cartilage) 2.​ Muscles 3.​ Circulatory System 4.​ Excretory system 5.​ Reproductive System 6.​ Inner layer of skin (dermis) 7.​ Outer layers of the digestive tube​ iii.​ Endoderm 1.​ The lining of the digestive tube and the structures that develop from it such as the respiratory system Stages in the Human Life Cycle 1.​ EMBRYO >> Conecepton -> end of 8th Week Single-celled zygote to an embryo, 3mm long 1g​ 2.​ FETUS >> 9th Week -> Birth Rapid growth, morphogenesis, cellular differentiation Cellular differentiation >> process in which a stem cell changes from one type to a differentiated one​ 3.​ NEONATE >> Birth -> 4 weeks Vital Physicological Adjustment​ 4.​ INFANT >> end of r weeks -> 2 years Deciduous (Temporary) teeth, nervous system, coordinated activities, language skills​ 5.​ CHILD >> 2 years -> Puberty Permanent Teeth, Muscular coordination, intellectual abilities​ 6.​ ADOLESCENT >> Puberty (11-14) -> Adult Primary and secondary sexual characteristics, motor skills, psychological changes, presumed adult responsibilities​ 7.​ YOUNG ADULT >> 20 years -> 40 years Peak of physical development, adult responsibilities (marriage, reproductive potential, career) After ri - Physiological change (aging)”​ 4  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin 8.​ MIDDLE AGE >> 40 years -> 65 years Aging, Menopause, Physical Changes​ 9.​ OLD AGE >> 65 years -> Death Period of senescence (health degradation), difficulty in reaching homeostasis Death - failure of cardiovascular/immune system Plant Development Plants are the way sunlight is captured in the ecosphere and stored in food for later slow catabolic release in the living cells of both plants and animals Tracheotypes >> Vascular Plants Seeds The seed plants are classified into two major groups based on their seed-bearing properties, ​ ➔​ GYMNOSPERMS ◆​ They are a group of seed-bearing plants that includes conifers, cycads, ginkgo, and gnetophytes ◆​ Gymnosperms = Naked seeds, based on the unenclosed conditions of the seeds​ ➔​ ANGIOSPERMS ◆​ A large group that includes herbaceous plants, shrubs, grasses, and most trees ◆​ They are further divided into Monocots (monocotyledons) and Dicots (Dicotyledons) MONOCOTYLEDON SEEDS ➔​ The seed is surrounded by a protective seed coat ➔​ Aleurone layer >> under the seed coat, DIGESTIVE ORGAN in seed germination ➔​ Endosperm >> FOOD STORAGE TISSUE, formed separately from the embryo ➔​ Coleorhiza >> protects future root, or radicle, as it grows ➔​ All of these structures will be discarded once they served their purpose, LEAVING ONLY THE RADICLE, the MESOCOTYL (Future Stem), and the SHOOT APEX, which by then will have developed into the mature versions of these structures​ DICOTYLEDON SEEDS ➔​ Have two Cotyledons ➔​ More typically as in beans and maples seeds, the Cotyledons serve as food storage in place of the endosperm ➔​ Other Dicot Seed structures: Radicle (root) and the plumule (shoot apex) 5  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ In most Dicot seeds, there is nothing comparable to the aleurone or coleorhiza, although some have a functional endosperm​ The embryo and its cotyledon(s) are the result of one of two distinct fertilizations: Endosperm (if any) is produced The other fertilization process produces the embryo, which yields a zygote, which then undergoes cleavage ◆​ The cell divisions that the zygote undergoes following fertilization first produce a: ​ basal cell >> develops a filament of cells called a suspensor ​ Terminal cell >> divides forming a rounded mass of cells; from this mass grows the two cotyledons and a central axis. In dicots, the part of the axis below the point of attachment of the cotyledon is called the hypocotyl, and the part above it is the epicotyl. ◆​ The embryo is in this state of development when the seed becomes dormant Seed Germination The embryonic plant is kept in a state of suspended development called dormancy, which ends when germination takes places Breaking Dormancy ➔​ First step, the embryo emits a hormone called gibberellin which diffuses through the seeds ➔​ In Monocots >> the hormone triggers the production of digestive enzymes by the aleurone ➔​ In Dicots >> the digestive enzymes are produced by the Cotyledons, these enzymes then proceed to break down the stored food in the endosperm or cotyledons (Ex: Amylase breaks down starch to form maltose, which is then cleaved by the maltase to yield glucose; and other enzymes attach stored proteins, fats, and oils, mobilizing them for seedling’s use) The Early Root Emergence ➔​ A close look at the root tip will show a cap consisting partly of dead or moribund (point of death) cells at its apex that protect the tender tissues from abrasion by the soil and also serve as a source of growth hormone ➔​ The actual living tissue is undergoing vigorous mitosis, which is why the root tip is known as the zone of division ➔​ It is an apical meristem, a growing tip of embryonic, differentiating tissue ➔​ By the time they begin to enlarge, they are left behind in a zone of elongation, which is responsible for most of the lengthwise growth of the root tip ➔​ Since new cells are constantly added to this zone by mitosis, however, growth continues indefinitely ➔​ Simultaneously, older portions of the zone of elongation cease to grow and become incorporated into the zone of maturation where tissue differentiation begins 6  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin Meristem and Buds Primary Meristems ➔​ Produces differentiated tissues such as phloem and xylem ➔​ Some tissues derived from the primary meristem remain undifferentiated and form the cambium layer of the stem and the similar pericycle layer of the root ➔​ These eventually form differentiated tissues themselves, but in a way to produces lateral growth and increase in girth The Leaf Bud ➔​ Leaf Growth ◆​ Each leaf originates on the side of the meristem, growing upwards as it enlarges and begins to differentiate. ◆​ Once growth is well underway, another group of cells next to it and somewhat above it begins to grow outward and upward ➔​ Leaf Fall ◆​ Leaves in all plants die, in some cases the plant senscence as a whole. ◆​ Xylem: ages, it becomes clogged with resin and becomes heartwood, Cell produced by Cork Cambiu, age, they die and become cork. ◆​ Deciduous Trees: Intentionally kills the leaves to conserve water in the cold​ ➔​ The Ecology of Abscission ◆​ Process by which plants shed one of their parts ◆​ Abscession later >> adaptation that permits the loss of leaves, represents a point of weakness so that in time, yellowed leaves are blown off by winter winds Secondary Growth In Dicots ➔​ If root and shoot (stem) meristems give rise to all plant tissues, a process of differentiation must occur behind the growing tips of the stem and the root ◆​ Stems: The earliest trace of differentiation occurs just behind the apical zone of active mitosis ​ In the center of the apical bud is a cylinder that develops into the vascular tissues as it matures, known as the provascular cylinder. ​ In the exterior, potential epiderms called the protoderm develop. ​ Between the two lies a layer called ground meristem or ground tissue, which becomes the cortex and the pith In Monocots ➔​ Secondary growth DOES NOT USUALLY OCCUR 7  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ The trunk of a treelike monocot, such as bamboo or a palm tree remains roughly the same diameter from base to crown. In fact, the diameter of a palm trunk can be somewhat smaller at the base than midway between it and the crown. Yet the trunk of a palm seedling is not as great as the mature tree. What happens is a bit different than what occurs in dicots ➔​ Behind the apical meristem is a primary thickening meristem that is as great in diameter as the trunk/ It is derived from the apical meristem which continuously enlarges to produce it ➔​ The primary thickening meristem then layson down vascular and other differentiated tissues to form the stem of the palm Animal Reproduction Animals can reproduce asexually and sexually. Asexual ➔​ >> creation of a new individual whose genes all come from one parent without fusion of egg and sperm ◆​ it enables animals living in isolation to produce offspring without locating mates ◆​ It can also create numerous offspring in a short amount of time, which is ideal for colonizing a habitat rapidly ◆​ Theoretically, asexual reproduction is most advantageous in stable, favorable environments because it perpetuates successful genotypes precisely ➔​ Mechanisms of Asexual Reproduction ◆​ Fission >> ​ Separation of a parent into two or more individuals of approximately equal size. The animal splits into two or more pieces, and each piece grows into a new animal. ​ (Ex: Sea Anemone)​ ◆​ Budding >> ​ A small "bud" grows out of the parent’s body. Eventually, it breaks off and becomes a new animal. ​ (Ex: Cnidarians and Tunicates)​ ◆​ Fragmentation >> ​ The animal’s body breaks into pieces, and each piece grows into a new animal. ​ (Ex: Flatworms)​ ◆​ Regeneration >> ​ A part of the animal’s body grows back after being lost, and in some cases, the lost part becomes a new animal. ​ (Ex: Sea Stars) 8  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin Sexual ➔​ >> Creation of offspring by the fusion of haploid gametes to form a zygote which is a diploid ◆​ Increases genetic variability (one of its advantages over asexual reproduction) among offspring by generating unique combinations of genes inherited from two parents. ◆​ Thus, by producing offspring having a variety of phenotypes, sexual reproduction may enhance the reproductive success of parents when environmental factors (including pathogens) change relatively rapidly. ◆​ Female gamete, unfertilized egg (AKA ovum), smaller motile cell ◆​ The male gamete, the sperm, is generally a much smaller, motile cell ➔​ Mechanisms of Sexual Reproduction ◆​ Sexual reproduction involves two parents. Each contributes a specialized gamete (an egg or sperm); these fuse to form the fertilized egg or zygote. Fertilization, the fusion of sperm and egg, may take place: ​ inside the body (internal fertilization). ○​ Female moist tissues provide the water medium required to move sperm ○​ Delivers sperm directly into the body ​ outside the body (external fertilization). ○​ Mating partners usually release eggs and sperm into the water simultaneously Reproductive Variations ➔​ Metagenesis ◆​ also known as ‘transformation development’, refers to an alternation of asexual(polyps) and sexual(Medusa) generations. ➔​ Parthenogenesis ◆​ also known as ‘virgin development’, is a form of reproduction in which an unfertilized egg develops into an adult animal. ◆​ This occurs for several generations, after which males develop, produce sperm, and mate with females to fertilize their eggs ◆​ In some species, parthenogenesis is advantageous in maintaining social order; in others, it appears to be an adaptation for survival in times of stress when there is a serious decrease in population. ◆​ (Ex: Honey Bees. The queen honeybee is inseminated by a male during the “nuptial flight”. The sperm she receives are stored in a little pouch connected with her genital tract but closed off by a muscular valve. As the queen lays eggs, she can either open this valve, permitting the sperm to escape and fertilize the eggs, or keep the valve closed, so that the eggs develop without fertilization. Generally, fertilization occurs in the fall, and the fertilized eggs are quiescent during the winter. The fertilized eggs become females (queens and workers); the unfertilized eggs become males (drones)) 9  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ Hermaphroditism ◆​ means that a single organism produces both eggs and sperm ◆​ this form of reproduction is still classified as sexual, (since both eggs and sperm are involved), ◆​ exception to the important generalization that sexual reproduction involves two different individuals.​ (Ex: Earthworm. Most hermaphrodites do not reproduce by self- fertilization. Rather, as in earthworms, two animals copulate, and each inseminates the other.) ◆​ Human Reproduction FEMALE REPRODUCTIVE ANATOMY ➔​ OVARIES >> Produce both the egg cell and the sex hormones. Enclosed in a tough protective capsule and contains many follicles. Egg cell is expelled from the follicle in the process of ovulation ➔​ OVIDUCTS (FALLOPIAN TUBE) and UTERUS >> Egg cell is released into the abdominal activity near the opening of the oviduct, or fallopian tube. The uterus is a thick, muscular organ that can expand during pregnancy to accommodate a 4-kg fetus. The inner lining of the uterus, the endometrium, is richly supplied with blood vessels. The neck of the uterus is the cervix, which opens into the vagina.​ ➔​ VAGINA and VULVA >> a thin-walled chamber that is the repository for sperm during copulation and that serves as the birth canal through which a baby is born. Vulva is a collective term for the external female genitalia. The vestibule, labia minora, labia majora, clitoris, and Bartholin’s glands are all located in this area having their special functions.​ ➔​ MAMMARY GLANDS >> present in both sexes but normally function only in women. They are not part of the reproductive system but are important to mammalian reproduction. Within the glands, small sacs of epithelial tissue secrete milk which drains into a series of ducts opening at the nipple. MALE REPRODUCTIVE ANATOMY ➔​ TESTES >> consist of many highly coiled tubes (seminiferous tubules – where sperm form) surrounded by several layers of connective tissue. he Leydig cells that are scattered between the seminiferous tubules produce testosterone and other androgens. The production of normal sperm cannot occur at the normal body temperatures of most mammals, and the testes of humans and many other mammals are held outside the abdominal cavity in the scrotum.​ ➔​ DUCTS >> From seminiferous tubules, the sperm pass into the epididymis. During ejaculation, the sperm are propelled from the epididymis through the muscular vas deferens. These two ducts (one from each epididymis) run from the scrotum around and behind the urinary bladder, where each joins a duct from the seminal vesicle, forming a short ejaculatory duct. The ejaculatory ducts open into the urethra, the tube that drains both the excretory system and reproductive system of a male. The urethra runs through the penis and opens to the outside at the tip of 10  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin the penis.​ ➔​ GLANDS >> Three sets of accessory glands—the seminal vesicles, prostate gland, and bulbourethral glands—secrete secretions into the semen, the ejaculated fluid.​ ➔​ Semen in the Female Reproductive Tract – males usually ejaculate 2-5 ml of semen, and each milliliter may contain 50-130 million of sperm. Prostaglandins in the semen cause thinning of the mucus at the opening of the uterus and stimulate contractions of the uterine muscles, which help semen move up to the uterus.​ ➔​ PENIS >> is composed of three cylinders of spongy erectile tissue derived from modified veins and capillaries. During sexual arousal, the erectile tissue fills with blood from the arteries. As this tissue fills, the increasing pressure seals off the veins that drain the penis, causing it to engorge with blood. The resulting erection is essential to insertion of the penis into the vagina. Introduction to Genetics Definition of Terms: ➔​ Nucleotide: the organic molecule that is the building block of DNA and RNA ➔​ Codon: series of three nucleotides within the DNA; directs the proteins within the cell to attach a specific protein to a series specified by the rest of the DNA GENETICS ➔​ Scientific studies of genes and heredity, or how variations in DNA sequence cause specific characteristics or traits to be passed from parents to offspring ➔​ Branch of Biology concerned with the DNA of organisms GENES ➔​ The most basic unity of inheritance, composed of DNA molecules that are transferred from parents to their offspring ➔​ Passed down from parents to offspring and contain the information needed to specify physiological and biological traits ➔​ Part of our genome that encodes the information for making those codes for specific proteins or segments of proteins ➔​ The human genome has roughly 20,000 protein-coding genes 11  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ Made up of DNA (Deoxyribonucleic acid) Genes >> DNA >> Chromosomes >> Nitrogenous Bases DNA (Deoxyribonucleic Acid) ➔​ Mostly located in the cell nucleus (Nuclear DNA) ➔​ Information in DNA is stored as code made up of four chemical bases Adenine (A), Guanine (G), Cytosine (C), Thymine (T) ➔​ NITROGENOUS BASE PAIRS:​ ​ A and T​ ​ C and G ➔​ Each base is also attached to a sugar molecule and a phosphate molecule ➔​ Each base pair is bonded through Hydrogen Bonds ➔​ The ratio of adenine is always equal to thymine and likewise for guanine and cytosine ➔​ The Backbone of DNA is composed of alternation deoxyribose sugar and phosphate ➔​ NUCLEOTIDES >> A base, sugar, and phosphate; they are arranged in two long strands. The blue part in the image is the nucleotide. Important Terms to Remember ➔​ Allele >> One of two or more alternative forms of a gene. ➔​ Dominant Trait >> Trait that is expressed, can be observed on the person ➔​ F1 Generation >> First “Filial” or first generation of offspring ➔​ F2 Generation >> generation produced by the interbreeding of the F1 Generation ➔​ Gamete >> reproductive/sex Cell ➔​ Genotype >> genetic composition of an individual ➔​ Heterozygous >> Organisms that have two different alleles for the same trait (Ex: Tt - Hybrid of Dominant and recessive trait of a certain trait) ➔​ Homozygous >> Organisms that have identical alleles for a particular trait (Ex: TT - Homozygous Dominant; tt - Homozygous Recessive) ➔​ Phenotype >> Observable characteristics of an individual 12  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ Punnet Square >> diagram used to predict the outcome of a particular breeding experiment ➔​ Recessive Trait >> Trait that is masked by the presence of the dominant trait Phenotype Vs. Genotype ➔​ Phenotype: observable traits, like blue eyes, brown hair, etc. ➔​ Genotype: Combination of alleles like TT, Tt, tt Dominant Vs. Recessive Trait ➔​ Dominant: the observable trait ➔​ Recessive: There but not observable History of Genetics Gregor Mendel ➔​ Father of Genetics ➔​ Experimented with Pea Plants for 8 Years (1856 - 1863). He grew over 10,000 Pea plants, keeping track of the progeny number and type ➔​ His experiment led to the formulation of the laws of inheritance​ Why Pea Plants? ➔​ Easy to grow ➔​ The traits are easily identified and observed ➔​ Can work with large numbers of samples Characteristics of the Pea Plant Observed ➔​ Seed Color, shape, and coat color ➔​ Flower position ➔​ Stem length ➔​ Pod shape and color Mendelian Vs. Non-Mendelian Genetics ➔​ Mendelian: Predicts; patterns of inheritance ➔​ Non-Mendelian: Does not follow Law of Inheritance Law of Segregation 13  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ Each Organism has two Alleles for each trait, but during the formation of gametes (Sperm/Egg Cell), the allele will separate (segregate); the gametes will only take on one allele. ➔​ Each Parent Passes an allele AT RANDOM to the offspring ➔​ It is only upon gamete formation that the allele separate (Ex: If a plant has two alleles for flower color (R for red and r for white), the 🧦* gametes will carry either R or r, not both.) *Analogy: Imagine your parents giving you one sock each for a pair — not both socks from the same parent! Law of Independent Assortment ➔​ Genes for different traits are inherited separately from each other, as long as they’re on different chromosomes ➔​ The genes do not influence one another on how they are sorted ➔​ Represented by the DIHYBRID EXPERIMENT​ (Ex: A pea plant’s seed color (yellow or green) and seed shape (round or wrinkled) are inherited separately. A plant with round yellow seeds doesn't guarantee round green seeds in the next generation. ➔​ Analogy: Think of picking an outfit. Choosing a blue shirt doesn't mean you must wear black pants—those choices are independent! 👕👖 Law of Dominance ➔​ When an organism has two different alleles for a trait, the Dominant allele will mask the recessive one ➔​ A trait is dominant when it is expressed instead of the other allele​ (Ex: If a pea plant has one allele for tall (T) and one for short (t), it will be tall because the tall allele is dominant.) ➔​ Analogy: Imagine two singers performing a duet — if one singer is much louder 🎤🎶 (dominant), that's the voice you'll hear! Sex Linkages and Genetic Recombination Sex Linkages ➔​ Refers to the phenomenon of genes being located on sex chromosomes (X or Y) 14  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ Describes the biological basis for how certain traits are associated with sex chromosomes​ (Ex: color blindness and hemophilia—which are located on the X chromosome)​ Male (XY) and Female (XX) Chromosomes ➔​ Males are more likely to inherit X-linked traits and exhibit recessive phenotypes than females because they only need 1 recessive allele to express the recessive trait. ➔​ The Y chromosome of Males is smaller than the X chromosome; therefore, fewer genes can fit in it. ➔​ Because Men’s Y chromosome holds fewer genes, only their X chromosome can inherit traits. Since only the X chromosome in men can inherit sex-linked traits, it would require only 1 recessive or Dominant allele to manifest a certain phenotype ➔​ Genes found on the X-chromosome, but not on the Y-chromosome are sex-linked ➔​ Since women have two X chromosomes, two recessive alleles are required to express a recessive phenotype. Because if even one Dominant allele is present, the dominant trait is expressed. ➔​ When writing Genotypes, we write the chromosome and then use the superscript to show the Allele, but since the Y-chromosome does not have genes, the superscript is left blank ➔​ The Y-linked traits are only inherited from Fathers to Sons because females do not have any Y-chromosome DNA Recombination ➔​ Process where genetic material is exchanged and rearranged between homologous chromosomes during Prophase I of Meiosis. This happens during the SYNAPSIS pairing of homologous chromosomes ➔​ “When chromosomes swap DNA” ➔​ This results in a new combination of alleles for the offspring ➔​ An important mechanism in sexual reproduction that increases genetic diversity within a population ➔​ DNA from one chromosome switches places with pieces of DNA from another chromosome, Each generation does its shuffle of genetic material ➔​ You inherit about 50% of your DNA from each of your parents, and about 25% of your DNA from each of your grandparents’ DNA; this can vary depending on how the DNA is shuffled (Ex: you can get more genetic information from your grandmother than your grandfather) Examples of X-linked Traits 15  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin ➔​ Color Vision Deficiency ◆​ Recessive hereditary disorder, where affected people cannot distinguish certain colors ◆​ Human genes associated with color vision are located on the X-chromosome is missing ◆​ Protanopia: Red Blindness ◆​ Deuteranopia: Green Blindness ➔​ Hemophilia ◆​ Disorder related to blood clotting ◆​ The gene that codes for an important protein for blood clotting is missing ◆​ People with this disorder can bleed to death from minor wounds and can suffer internal bleeding from bumps or bruises. Pedigree chart ➔​ Shows relationships between family members ➔​ Indicates which individuals have pathogenic variants, traits, and diseases within a family, as well as vital status ➔​ It can be used to determine disease inheritance patterns within a family ➔​ Autosomal: Both males and females are affected, and all generations are affected then it is autosomal dominant. But if both males and females are affected but it phenotypically skips a generation, there can be carriers in the generation, but if none of the members of that generation exhibit the trait then it is autosomal recessive. CLUE: if the gender is not given, then it is automatically autosomal. If the generation only has carriers, then it is also autosomal recessive. ➔​ Y-linked: only the males are affected ➔​ X-linked: the pattern of inheritance is only affecting females ➔​ When making a pedigree chart, the gender is not given. Assume 50- 50, the same number of male and female offspring ➔​ If you are asked to determine the probability that the trait will be passed on to their offspring, conduct a punnet square. If ever there is no specified partner, assume that the individual is with an unaffected partner. SA#1 Retest Review Animal Development 1.​ Early stages: from one cell to many​ - zygote: fertilized egg that will develop into an individual​ - Cleavage: Cell division without growth​ 16  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin - 2 > 4 > 8 > 16 (Morula)​ - Blastocyst: Formed from cleavage cells, inner mass soon becomes the embryo 2.​ Implantation: Start of Pregnancy​ - happens 7 days after fertilization​ - Embryo attaches itself to the uterus lining (endometrium)​ - Tiny blood from maternal capillaries become the source of nutrient 3.​ Formation of Germ Layers​ - Ectoderm (Outermost): Brain, Nervous system, skin​ - Mesoderm (Middle): Blood, muscle, bones​ - endoderm (Innermost): Digestive system, Lungs Developmental stages: 1.​ Embryo (conception - 8 weeks) - formation of body structures 2.​ Fetus (8 weeks - birth) - rapid growth and development 3.​ Neonate (Birth - 4 weeks) - adaptation to new environment 4.​ Infant (4weeks - 2yo) - formation of teeth, movement, and nervous system 5.​ Child (2y - puberty) - Muscles, permanent teeth, brain development 6.​ Adolescent (Puberty (11-14) - Adulthood) - Development of reproductive organs, body changes 7.​ Young Adult (20 -40 years) - peak physical condition, career, and life 8.​ Middle age (40 - 65 yo) - body begins aging, women begin menopause 9.​ Old age (65+ yo) - body slows down, homeostasis becomes harder Plant Development Importance of plants: -​ 99% of living organisms are plants -​ Plants absorb sunlight to create food for themselves and animals -​ Plants are made of stem, leaf, and roots Types of plants -​ Gymnosperms: Naked seed -​ Angiosperms: seeds protected by flower Types of Angiosperms: -​ Moncots: have one cotyledon, energy is from outer layer, which digests food -​ Dicots: have to cotyledons, one cotyledon is for nutrients 1.​ Seed Germination​ - Dormancy, seed becomes inactive until conditions are right​ 17  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin - Dormancy is broken, Gibberellin is released to initiate digestion of stored food for energy​ - Root and Shoot growth, root downward for anchorage, shoot tip upward to develop leaves and stems 2.​ Plant Growth:​ - Primary growth, plant increases in length from apical meristems (roots and shoots)​ - Secondary growth: Increases thickness, especially in dictos 3.​ Leaf growth and abscission​ - Leaves grow from leave buds near the meristems​ - leaf fall (Abscission): part of the natural cycle to conserve water. Animal Nutrition Caloric energy -​ Unit of energy representeing amount of heat required to raise the temperature of 1kg of water by 1C -​ Number of calories in food determines energy content Nutritional Requirements of Animals -​ Carbohydrates (4 Calories per g): Major energy source, from wheat, grain, cereals -​ Proteins (4 Calories per g): used for cell structure, enzymes, and hormones; found in dairy, meats, and fish -​ Fats (9 Calories per g): Used for cell membrane, hormones, and insulation; from butters, oils, and processed foods Essential Nutrients: Cannot be Produced by the body -​ Essential Amino acids: 8 needed for protein synthesis -​ Essential Fatty acids: needed for making membrane lipids -​ Vitamins, organic molecules for metabolism -​ Trace elements/minerals: inorganic nutrients needed in small amounts Food uptake in Cells (Endocytosis) -​ Phagocytosis: Engulfment of large particles -​ Pinocytosis: uptake of extracellular fluids -​ Receptor-mediated endocytosis: uptake of specific solutes using receptor-coated pits Type of Animals Based on Feeding Methods -​ Filter-feeders: taking in water and then filtering out food -​ Substrate feeder: living inside the food source -​ Fluid feeders: sucks in nutrients from a host -​ Bulk Feeders: feeds large amounts of food using specialized strucutres Other modes of Animal Feeding -​ Saprophytic: feeding on decaying organisms -​ Parasitic: relies on host for nutrients 18  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin -​ Ecto parasitic - outside -​ Endoparasitic - inside -​ Holozoic: can consume solid/liquid foods -​ Omnivores -​ Herbivores -​ Carnivores -​ Photoautotrophic: gets food from the sun -​ Chemotrophic: use chemicals to synthesize organic matter Plant Nutrition How do plants make their own food?: -​ They use photosynthesis -​ They use CO2, O2, sunlight, water, and sugar -​ Glucose provides energy for the plants, while oxygen is released into the air Nutrients Plants need to grow: They need nutrients beyond sunlight and water -​ Macronutrients: needed in large amounts -​ Micronutrients: Needed in small amounts 19  GENERAL BIOLOGY 2​ ℅ Shanjay Aberin Too much fertilizer can harm plants, making the soil too salty, causing OSMOTIC stress (Water imbalance) Parasitic Plants -​ Holoparasites: fully dependent on the host, cant do photosynthesis -​ Hemiparasites: can do photosynthesis, but still rely on the host for water and nutrients 20