Biology Stage 2 Topic 2

Cells as the Basis of Life

organisms

living things

multicellular

organisms made up of two or more cells

unicellular

organisms made up of only one cell

movement

All living things move, whether it is animals moving through their environment or plants turning towards light

respiration

The process of producing energy (ATP) from nutrients within cells

sensitivity

The ability to detect and respond to environmental changes or stimuli

growth

A permanent increase in size or cell number

reproduction

The ability to produce offspring to ensure the survival of the species

excretion

The removal of metabolic waste materials produced by cells.

nutrition

The intake and utilization of nutrients for energy, growth, and development. 

viruses

small non-living structures that can respond to stimuli, cause disease, and multiply

viruses are not considered living things because

they do not directly use energy, cannot actively maintain structure, and cannot reproduce independently

cell theory states that

all living organisms are made from cells or the products of cells, all cells arise from pre-existing cells, all cells contain hereditary material

organelles exclusive to plant cells

vacuoles, chloroplasts, cell wall

organelles exclusive to animal cells

lysosomes, centrosomes

nucleus

controls cell function through enzyme production

nuclear envelope

the double membrane surrounding the nucleus—contains nuclear pores

chromatin

DNA coiled around proteins, condenses to form chromosomes

nucleoli

membrane-less structures within the nucleus; assembles rRNA and ribosomal subunits for protein synthesis

mitochondrion/mitochondria

membrane-bound structures; generates ATP—used as a source of chemical energy through aerobic respiration

chloroplasts

organelles containing chlorophyll—surrounded by two closely-positioned membranes

thylakoids

flattened sacks inside chloroplasts containing chlorophyll; often arranged in grana stacks

grana

stacks of thylakoids; functions as the primary site for the light-dependent reactions of photosynthesis

stroma

the fluid-filled interior of chloroplasts in plants (essential for photosynthesis) and the connective tissue framework of organs in animals (present in both plants and animals)

vesicle

small, temporary structures; primarily transport materials and are involved in metabolism

vacuole

large, permanent structures; mainly used for storing water, nutrients, or waste

vacuole/vesicle composition

contain ions, simple sugars and amino acids in a watery solution; this helps plant cells maintain the water-salt balance in the cytoplasm—helps maintain the cell’s structure and stability

ribosomes

act as the site for incorporation of amino acids into polypeptides; primary site of protein synthesis

role of ribosomes in bonding

facilitate the formation of peptide bonds between amino acids.

rough endoplasmic reticulum structure

series of flattened membranes, embedded with ribosomes—is continuous with the nuclear membrane

rough endoplasmic reticulum function

isolates proteins secreted by the cell and transports them to Golgi apparatus

smooth endoplasmic reticulum structure

consists of tubular membranes; ribosomes are absent

smooth endoplasmic reticulum function

production and secretion of lipids

Golgi apparatus structure

consists of a stack of cisternae sacs that form a series of flattened structures; often surrounded by vesicles and tubules

Golgi apparatus function

modifies, sorts, and packages proteins and lipids received from endoplasmic reticulum into vesicles for delivery

lysosomes

Contain powerful digestive enzymes to break down materials inside the cell; rid the cell of

toxins and are used by white blood cells to destroy pathogens.

contain powerful enzymes that digest materials inside the cell and excrete toxins from the cell; used by WBC to destroy pathogens

cytoskeleton

internal and dynamic framework that can be rapidly removed or inserted into an existing structure to alter its shape; comprised of protein molecules

cytoskeleton function

provides structural support, maintains cell shape, enables mobility, organises organelles, and facilitates intracellular transport