Biology Term 1

Requirements for life

Movement

Reproduction

Stimuli

Homeostasis

Grow

Respiration

Excrete

Nutrients

Textbook Work

1.1 Prokaryotic cells

• are single cells and are classified into 2 domains: bacteria and archaea

• are the simplest type of cell

• they contain a granular cytoplasm that carry out the chemical reaction of life

• genetic material is contained in a singular chromosome of DNA

• both prokaryotic and eukaryotic cells contain ribosomes which create protein

1. Describe the nature and location of genetic material in prokaryotic cells

The genetic material consists of a double stranded DNA molecule and is located in the cytoplasm

2. Identify one structure in a prokaryotic cell

a singular circular chromosome in the nucleoid region

3. Describe what plasmids are

a small ring of DNA that is not a chromosome

4. Explain the main limitation of not having membrane-bound organelles

limits the ability to complete multiple cell processes simultaneously

1.2 Eukaryotic cells

• have a number of membrane-bound organelle

• the nucleus consists of a nuclear membrane which contains the chromatin, the nucleolus and the nucleoplasm

• each chromosome consists of a strand of DNA

• the cell activity is controlled by the information in the DNA

• chloroplast are cell organelles where photosynthesis occurs

• they have a double membrane and contain chlorophyll, enzymes, thylakoids and stroma

• thylakoids are stacked into grana and sit in the stroma

• photosynthesis uses light, water and carbon dioxide

• it produces glucose and oxygen

• light energy is changed into chemical energy by chlorophyl

• mitochondria are where cellular respiration happens

• respiration uses glucose and oxygen to make carbon dioxide and water

• mitochondria have folded inner membranes called cristae for more reaction space

• they contain their own DNA and ribosomes

• rough ER is covered in ribosomes and makes proteins

• proteins are folded and modified in the ER before going to the Golgi apparatus

• ribosomes make proteins from amino acids

• proteins are needed for growth, repair, enzymes and hormones

• ribosomes have two subunits and are not membrane bound

• smooth ER makes lipids and carbohydrates and helps with detoxification

• the golgi apparatus is an organelle that processes, sorts and packages newly formed proteins for transport

• lysosomes are spherical vesicles that are involved in the recycling of cellular material

• they contain enzymes that can break down almost all types of biomolecules

• vacuoles occur in both animal and plant cells

• centrioles are important in cell replication

• the cytoskeleton helps provide structure and organisation in a cell

1. Match each structure with its function

• nucleus = control centre

• endoplasmic reticulum = synthesis and transport

• lysosomes = breakdown of materials

• mitochondria = cellular respiration

• chloroplasts = photosynthesis and storage

2. Identify the substance produced by the smooth ER

lipids, phospholipids and cholesterol, and steroid hormones

3. Describe the role of the rough ER

produces proteins for export, modify them, and transport them to the Golgi apparatus

4. Explain the difference between

a) chlorophyll and chloroplast

• chlorophyll is the green pigment inside the chloroplast that absorbs light energy

• chloroplasts is the entire organelle in plants where photosynthesis happens

b) rough and smooth ER

• rough ER is studded with ribosomes

• smooth ER doesn’t have ribosomes

c) a chloroplast and mitochondria

• chloroplasts uses sunlight to produce sugar

• mitochondria breaks down sugar to produce ATP

5. Explain why plant cells still need mitochondria despite being able to make their own food

to breakdown the sugars created in photosynthesis to produce ATP

6. Explain why you would expect to find more mitochondria in muscle cells than in skin cells

they need more energy demands for contraction and movement

1.3 Comparing prokaryotic and eukaryotic cells

• the most distinguishing difference is its presence or absence in the nucleus

• prokaryotic cells contain a single circular chromosome that is located with the cytoplasm

• the chromosomes of eukaryotic cells are separated from the cytoplasm

1. Identify the features that are common to all cells

a plasma membrane, cytoplasm, DNA

2. State the evidence for a common evolutionary origin of mitochondria and chloroplasts

• scientists believed they evolved from endosymbiosis (where one species lives inside another)

• can only be formed from a pre-existing mitochondria and chloroplast

3. Identify features that are unique to:

a) prokaryotic cells

• the absence of a membrane-bound nucleus and organelles

b) eukaryotic cells

• a membrane bound nucleus containing DNA

• numerous membrane bound organelles

• complex cytoskeleton

4. Explain the difference between cytoplasm and cytosol

• cytoplasm is the entire content within a cell membrane

• cytosol is specifically the fluid part of the cytoplasm excluding organelles

Cell Theory

all living organisms are composed of cells —> cells are the functional units of organisms —> cells come from existing cells

Cell membrane

Describe the structure and function of cell membrane

• fluid mosaic model

• protein channels

• phospholipids

• cholesterol

• glycoprotein

Cell membrane experiment

In the experiment, the dialysis tubing represented the cell membrane, which is semi-permeable because it selectively allows substances in and out of the cell. The starch molecules inside the tube were too large to move through the tube by simple by simple diffusion - they would need a protein channel to allow facilitated diffusion. The iodine molecules are small and can pass through via simple diffusion, moving from high concentration outside the tube, into the low concentration inside the tube. This is passive transport that does not require energy as it uses the concentration gradient. The molecules will continue to diffuse until an equilibrium is reached. (Iodine reacts with starch, turning purple)

Osmosis

refers to the movement of water from an area of high water concentration to an area of low water concentration across a semipermeable membrane

Hypotonic

A hypotonic solution is a solution with a lower solute concentration (high water concentration)