VCE Biology (Unit 1)

Cell

The basic unit of structure and function in organisms (living things)

Cell Theory

All living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

Prokaryote

Type of cell that does not have a nucleus or any membrane-bound organelles

Eukaryote

A cell that contains a nucleus and membrane-bound organelles

Cytoskeleton

Network of protein filaments within some cells that helps the cell maintain its shape.

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Cytosol

Fluid portion of cytoplasm

Chloroplast

An organelle found in plant cells where photosynthesis occurs

Vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

Nucleus

An organelle of the cell containing DNA and RNA and responsible for growth and reproduction

Nucleolus

Found inside the nucleus and produces ribosomes

Mitochondria

An organelle found in large numbers in most cells, in which the biochemical processes of cellular respiration occur

Ribosome

Site of protein synthesis

Endoplasmic Reticulum (ER)

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

Rough Endoplasmic Reticulum

An endomembrane system covered with ribosomes where many proteins for transport are assembled.

Smooth Endoplasmic Reticulum

An endomembrane system where lipids are synthesized, calcium levels are regulated, and toxic substances are broken down.

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

Vesicle

Small membrane-bound sac that functions in moving products into, out of, and within a cell

Lysosome

An organelle containing digestive enzymes

Cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

Flagellum

A long, hairlike structure that grows out of a cell and enables the cell to move

Surface area to volume ratio

Ratio of a cell's outside surface area to its internal volume

Plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells and controlling transport of substances into/out of a cell

Semipermeable

Membranes that allow some substances through but not others

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail

Glycoproteins

A protein in the membrane that is involved in intercellular communication

Fluid mosaic model

Model that describes the arrangement and movement of the molecules that make up a cell membrane

Diffusion

The net movement of a substance from an area of higher concentration to an area of lower concentration, towards equilibrium (down the concentration gradient)

Concentration gradient (diffusion)

The direction of movement of a substance from higher concentration to lower concentration

Osmosis

Net movement of water molecules across a partially permeable membrane

Facilitated diffusion

The transport of substances through a cell membrane along a concentration gradient with the aid of channel or carrier proteins

Isotonic

Fluid outside the cell (intercellular) is the same as fluid inside the cell (intracellular). No net movement of water into or out of the cell.

Hypotonic

solute concentration outside the cell is lower than the solute concentration inside a cell

Hypertonic

solute concentration outside the cell is higher than the solute concentration inside a cell

Carrier proteins

Bind to specific molecules on one side of the membrane, change shape and release the substance on the other side

Channel proteins

Form a narrow passage through which water-soluble substances diffuse rapidly from an area of high concentration to an area of low concentration

Active transport

The movement of a substance across a cell membrane from an area of lower concentration to an area of higher concentration, requiring cellular energy (ATP)

Endocytosis (Bulk transport)

Parts of the membrane fold around the material and pinch off. Materials are enclosed in a vesicle inside the cell. Require energy.

Exocytosis

Elimination of some waste and secretion of cell products. Vesicle containing material fuses with the cell membrane, opens and spills contents into intracellular fluid. Requires energy.

Autotroph

An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

Heterotroph

Organism that obtains energy from the foods it consumes; also called a consumer

Photosynthesis

Process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches

Stoma

Fluid portion of the chloroplast; outside of the thylakoids

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

Cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

Aerobic cellular respiration

Respiration that requires oxygen. Occurs in the mitochondria. C6H12O6 + 6O2 --> 6CO2 + 6H2O

Anaerobic respiration

Respiration that does not require oxygen

Vascular plants

Have tissues made of cells that transport water and nutrients throughout the plant

Xylem

Vascular tissue that carries water upward from the roots to every part of a plant. dead.

Phloem

Living vascular tissue that carries sugar and organic substances throughout a plant

Transpiration

Evaporation of water from the leaves of a plant

Arteries

Carry blood away from the heart

Veins

Carry blood back to the heart

Capillaries

Microscopic vessel through which exchanges take place between the blood and cells of the body

Structural adaptation

A physical feature of an organism's body having a specific function that contributes to the survival of the organism

Physiological adaptation

A physical or chemical event that occurs within the body of an organism and enables survival

Behavioural adaptation

Actions of individuals or groups which increase the chances of survival and reproduction

Negative feedback

A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

Positive feedback

A physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change

Vasoconstriction

The constriction of blood vessels, which reduces heat loss to the external environment

Pancreas

Regulates the level of sugar in the blood

Organelles

A small cell structure that carries out a specific function within the cell

Purpose of cellular respiration

To break down glucose molecules to produce ATP as a more usable form of energy

Purpose of cell replication

growth and development, maintenance and repair, reproduction

Binary fission

Less complex and faster process of cell reproduction in prokaryotic cells - example of asexual reproduction. Includes DNA replication, chromosome segregation and cytokenesis. Mitochondria and chloroplasts divide via the process to form new organelles.

Mitosis

Instructions for growth and development are passed from one generation of cells to the next via division of the nucleus.

Cell cycle

Sequence of events that take place from one cell division to another.

Phases of cell cycle

G1 - Cell makes new proteins, grow and carries out normal functions, S (Synthesis) - DNA is copied, G2 - preparation for cell division, M (Mitotic) - Cell divides into two daughter cells

Phases of mitosis

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Interphase

Chromosomes are not visible. DNA strands are loose. Centrioles may be visible.

Prophase

Visible pairs of chromatids. Centrioles move to opposite ends of the cell. Nuclear membrane breaks down.

Metaphase

Chromatid pairs move to the centre of the cell. Centrome of each pair is attatched to a spindle fibre.

Anaphase

Chromatids seperate at the centromere. Chromatids are independent.

Telophase

Two sets of chromosomes. New nuclear envelope forms.

Cytokinesis

Cytoplasmic division occurs

Apoptosis

Programmed cell death

Proto - oncogenes

Code for proteins that stimulate cell division

Tumour-suppressor genese

Limit cell division

Benign tumour

Slow growing and enclosed in a capsule that prevents them from spreading

Malignant tumour

Can invade nearby tissue or enter the bloodstream/lymphatic system. (cancerous)

Stem cells

undifferentiated cells. Means they have no specific function.

Totipotent

Zygote - First cell produced following fertilization. Can differentiate into any cell type.

Pluripotent

Embryonic stem cells - Found in the early stages of a developing embryo. Can differentiate into multiple cell types.

Multipotent

Adult stem cells - Found in the bone marrow which contain blood stem cells. Can differentiate into a limited number of specialised cell types that belong to a specific tissue/organ.

Germ layers

endoderm, mesoderm, ectoderm

Endoderm (innermost layer)

stomach cells, pancreatic cells, liver cells. specialised cells.

Mesoderm (middle layer)

Skeletal muscle, smooth muscle, cardiac muscle, red blood cells, bone cells

Ectoderm (outer layer)

Neuron, skin cells, pigment cells

Main roles of digestion

Ingestion, digestion, absorption, egestion

organs in the digestive tract

mouth, esophagus, stomach, small intestine, large intestine

Adaptation

An inherited characteristic that increases the likelihood of survival and reproduction of an organism or species

Types of Adaptations

Structural, Physiological, and Behavioural

structual adaptations

Anatomical or morphological features that help organisms survive in a specific environment (wht their bodies are built with - inside and outside).

Physiological adaptations

An internal body process to regulate and maintain homeostasis for an organism to survive in the environment in which it exists (biochemical reactions (homeostasis), prodcution of chemicals, toxins etc).

Behavioural adaptations

What an organism does to survive in the unique conditions of its environment.

Homeostasis

Ability of the body or a cell to seek and maintain equilibrium within its internal environment when dealing with external changes

Negative Feedback

Mechanisms that cancel the feedback

Positive Feedback

Mechanisms that enforce or strengthen the original stimuli

Thermoregulation

Process that allows your body to maintain its core internal temperature.