Science Reviewer Q3 - Nervous System, Reproductive System, DNA PDF

SCIENCE REVIEWER Q3 BY CUTIE **NERVOUS SYSTEM** The **Nervous System** is the [major control system] of **homeostasis**. [It provides monitoring, response, and regulation of all systems in the human bod]y and other organisms. **Two Main Parts:** **Central Nervous System (CNS)** - [main "proce...

SCIENCE REVIEWER Q3 BY CUTIE **NERVOUS SYSTEM** The **Nervous System** is the [major control system] of **homeostasis**. [It provides monitoring, response, and regulation of all systems in the human bod]y and other organisms. **Two Main Parts:** **Central Nervous System (CNS)** - [main "processing center"] for the entire nervous system - [brain and spinal cord] **Peripheral Nervous System (PNS)** - [connects the brain and spinal cord to the other body parts] - [made up of nerves] **Brain** [Organ that controls the body]\'s functions, including movement, thought, and memory. **3 Parts of the Brain** - **Cerebrum-** the [largest part of the brain] (thinking, learning, memory, and speech) - **Cerebellum**- [located under the cerebr]um, (balance, posture, and fine motor movement) - **Brain stem-** [connects the brain to the spinal cord] (breathing, heart rate, seeing, hearing, talking, walking, eating) **The nervous system plays a crucial role in [detecting stimuli and coordinating responses]. ** **Stimulus** A [change in the environment] that causes a living organism to respond. **Types of stimuli** **External stimuli-** changes outside an organism, such as [sound, light, heat, smells, temperature changes, touch] **Internal stimuli-** changes within an organism, such as [hunger, thirst, pain, or blood pressure] **Response** An [action or reaction to a change in the environment] (stimulus) - **Positive responses-** moving towards a stimuli - **negative responses-** moving away from stimuli **Examples of response to stimulus:** - **Phototropism:** A plant growing towards a light source.  - **Geotropism:** Roots growing downwards due to gravity.  - **Thigmotropism:** A plant curling its leaves when touched (like a \"touch-me-not\" plant).  - **Pupil dilation:** The pupils of the eyes adjusting to different light levels.  - **Reflexes:** A quick, involuntary response like withdrawing your hand from a hot stove.  - **Muscle contraction:** Muscles contracting when stimulated by a nerve signal.  **Humans:** - - - - - **Neuron (Nerve Cell)** The [basic unit of the nervous system.] **Parts of Nerve Cell/Neuron:** - **Dendrites-** [branch-like structures that receive messages] for the cell - **Cell Body-** [contains the nucleus], golgi body, endoplasmic reticulum, mitochondria, and other components - **Axon-** [a long, thin nerve fiber], [carries electrical impulses from a neuron\'s cell body to another neuron/nerve cell] **Neurotransmission** - the [transfer of information between neurons] **Neurotransmitter** - a [chemical substance produced by the neurons] **REPRODUCTIVE SYSTEM** The ***reproductive system* also known as the genital system**, is the [biological system made up of all anatomical organs involved in sexual reproduction]. It includes the [male reproductive system which functions to produce and deposit sperm]; and the [female reproductive system which functions to produce egg cell], and to protect and nourish the fetus until birth **MALE REPRODUCTIVE SYSTEM** The male reproductive anatomy **external structures**: 1. **Penis** -- for sexual intercourse where [semen contains sperm is expelled or ejaculated] 2. **Scrotum** -- the [loose pouch -- like sac of skin] that hangs behind the penis which [contains the testicles]. 3. **Testicles (Testes)** -- oval organs about [the size of very large olives] that is [responsible for making testosterone] (the primary sex hormone and for producing sperm) 4. **Epididymis** -- [a long, coiled tube that rests on the backside of each testicle]. It [carries, store, and bring the sperm to maturity.] The male reproductive anatomy **internal organs**: 1. **Vas Deferens** -- [a long muscular tube that travels from the epididymis into the pelvic cavity behind the bladder]. It [transports mature sperm to the urethra for ejaculation] 2. **Ejaculatory Ducts** -- formed by [the fusion of the vas deferens and the seminal vesicles] 3. **Urethra** -- [tube that carries urine from the bladder and semen to outside of the body] 4. **Seminal vesicles** -- a [sac -- like pouches that attach to the vas deferens] near the base of the bladder, it [produces a sugar -- rich fluid (fructose)] that [provides sperms with a source of energy and helps with the sperms' motility (ability to move)]. 5. **Prostate gland** -- [a walnut -- sized structure that is located below the urinary bladder] in front of the rectum. It [contributes additional fluid to the ejaculate, and help to nourish the sperm.] 6. **Bulbourethral glands or Cowper's gland** -- [a pea -- sized structures located on the sides of the urethra] below the prostate gland. [Produce a clear, slippery fluid that serves to lubricate the urethra] and to [neutralize any acidity] due to residual drops of urine in the urethra. **Pathway Of Sperm Cells** Testicles - Epididymis -- Vas deferens - Ejaculatory duct -- Urethra **FEMALE REPRODUCTIVE SYSTEM** **External structures** of the female reproductive system: 1. **Labia majora** -- [the "large lips" that enclose and protect the other external reproductive organs of female] 2. **Labia minora** -- [the "small lips" that lies inside the labia majora], it surrounds the openings to the vagina and urethra. 3. **Bartholin\'s glands** [-- located besides the vaginal opening and produce a fluid (mucus)] secretion. 4. **Clitoris** -- [small, sensitive protrusion where two labia minora meet]. It is [covered by a fold of skin called prepuce.] **Internal organs** of the female reproductive system: 1. **Vagina** -- ["birth canal"], it [joins the cervix to the outside of the body.] 2. **Uterus (womb)** -- a [hollow, pear shaped that is the home to a developing fetus] divided into two parts: a. **Cervix** - the [lower part that opens into the vagina]. b. **Corpus** -- [main body of the uterus that easily expand to hold a developing baby.] 3. **Ovaries** -- [small, oval -- shaped glands that are located on either side of the uterus]. It [produces eggs and hormones.] 4. **Fallopian tubes** -- [narrow tubes that are attached to the upper part of the uterus and serve as tunnels for the ova (egg cells)] to travel from the ovaries to the uterus. It is where [the fertilization of an egg by a sperm occurs]. **Fertilization** The [process of a sperm and egg uniting to create a zygote], which is the [first stage of pregnancy.]  **MENSTRUATION** The [process in which blood and other tissues are shed from the uteru]s and [leave the body through the vagina]. It is also called a [menstrual period or menses.] On average[, an ovary releases only one egg every 28 days]. Hormones control many of the changes in the reproductive system. **Menarche (the first menstrual cycle)** - normally occurs between the [ages of 11 and 15] **Menopause-** between the [ages of 45 and 55] **Menstrual Cycle** - **PHASE 1: Menstruation Phase** - The [thickened uterine lining falls away], so the [body can start preparing a new one.] - **PHASE 2: Follicular Phase** - Hormones [creation of follicles on the ovaries]. Usually just [one follicle will mature into an egg.] - **PHASE 3: Ovulation Phase** - [The mature egg is released from the follicle] and is [ready for fertilization]. Follicle [will mature into an egg]. - **PHASE 4: Luteal Phase** - [If there is no fertilized egg, your body will prepare to shed its thickened lining], and [the cycle will begin again with menstruation.] **DNA** **DNA or Deoxyribonucleic Acid**, is [a molecule which contains all the instructions that an organism] requires to develop, live and reproduce. **Nucleotides** are the basic building blocks of DNA. - **sugar group-** [deoxyribose ] - **phosphate group-** a chemical group [made up of one phosphorus atom and four oxygen atoms] - **nitrogenous base-** adenine (A), cytosine (C), guanine (G), thymine (T) **Four Types Of Nitrogenous Bases:** **Adenine (A) -- Thymine (T)** **Guanine (G) -- Cytosine (C)** The [shape of the DNA] is a **double helix, like a twisted ladder.** Each side of a ladder is [composed of alternating sugar molecules and phosphate molecules.] **RNA** Another [type of nucleic acid] is called **RNA (Ribonucleic Acid)** but [RNA is single stranded] found mainly in the **cytoplasm** of the cell. **Nucleotides** are the basic building blocks of DNA. - **sugar group-** [ribose ] - **phosphate group-** a chemical group [made up of one phosphorus atom and four oxygen atoms] - **nitrogenous base-** adenine (A), cytosine (C), guanine (G), uracil (U) **Four Types Of Nitrogenous Bases:** **Adenine (A) -- Uracil (U)** **Guanine (G) -- Cytosine (C)** **Three major types of RNA:** **Messenger RNA (mRNA)** **Ribosomal RNA (rRNA)** **Transfer RNA (tRNA)** **REPLICATION** The process of [copying a cell\'s DNA before it divides] to [produce two identical DNA molecules], each molecule is [composed of one half of the original DNA strand and one half of the old DNA strand] that are [complementary with each other.] **Process:** - **Unzipping-** [DNA molecule unzips and the enzyme called **helicase** breaks down the hydrogen bonds] between the complementary base pairs. The double helix of DNA opens and [the strands separate.] - **Priming-** The cell then [creates short sequences of RNA called primers], which are synthesized by primase, that provide a [starting point, as a preparation for the next step.] - **Elongation**- An enzyme called DNA **polymerase** is [used to form new strands when the complementary nucleotides are added to each strand], this is the step where the [new DNA molecule is built.] **ENZYMES** [Proteins that speed up biological reactions.] **KEYPLAYERS In DNA Replication** **MUTATION** A [change in the DNA sequence of an organism alters individual genes.] Mutations [can be caused by errors in DNA replication], [exposure to chemicals or radiation], or [viral infections. ] **Point Mutation-** [Change in sequences of bases in normal hemoglobin] and the one affected by mutation. These are mutations where [a change a single base pair occurs.] - **Insertion mutation-** occurs when an [extra base pair is added to a sequence of bases]. - **Deletion mutation-** occurs when [a base pair is deleted from a sequence]. A deletion error can happen for many reasons. It may be due to radiation, chemicals, or just a broken protein that fails to insert **nucleotide bases.** With one or two bases added or deleted, all of the three-base codons change. This is called a **frameshift mutation.** **GENETIC DISORDERS** [Caused by an abnormality in the genetic makeup of an individual]. Some people [inherit genetic disorders from the parents], while acquired changes [or mutations in a preexisting gene] or group of genes cause other genetic disorders. **Monosomy**- the condition where an individual is missing one copy of a chromosome **Trisomy-** having an extra copy of a chromosome **Polyploidy-** the presence of an entire extra set of chromosomes **Some of these genetic disorder are:** - **\"Down\'s syndrome\" or Trisomy 21-** a person has three copies of chromosome 21 - **"Edwards\' syndrome" or Trisomy 18-** a person has three copies of chromosome 18 - **"Patau syndrome" or Trisomy 13-** a person has three copies of chromosome 13 - "**Klinefelter syndrome"-** have one or two extra sex chromosome(s) **EVOLUTION** [The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms] during the history of earth. [Organisms inhabiting the earth have changed over time], [their structures], [traits], and [abilities] allowed them to [adapt and survive in their environment] **Evidences for Evolution** - **Fossils-** traces of organisms that lived in the past and were preserved by natural process or catastrophic events. - **Imprints-** shallow external molds left by animal or plant tissues with little or no organic materials present - **Compression-** preserved in sedimentary rock and is formed with more organic material most commonly in environments where fine sediment is deposited - **Determine The Age Of Fossils** - **Relative Dating-** age of rock is compared to the other rock layer - **Radiometric Dating-** using the decay of radioactive isotopes of Carbon-14 which is present in rocks when the organism died. - **Comparative Anatomy-** the [study of the similarities and differences in the structures of different species] - **Homologous structures-** Refer to the [body parts of an organisms that may perform different functions but of the same origin]. - The forelimbs of dog, bird, lizard, and whale, which are [structurally the same, but functionally different are examples of homologous structures.] - It is a strong indicator that the [organisms evolved from common ancestors.] This type of evolution is called **[divergent evolution.]** - **Analogous structures-** [body parts of an organism that may perform the same function but of different origin] - Wings of birds, bats, and insects that have the [same function but different in origin are example of analogous structures.] - This type of evolution is called **Convergent Evolution** **THEORIES OF EVOLUTION**