Bio Topic 3 -> Cell ultrastructure

Identify these cell organelles

What is the structure of the nucleus

• has a double membrane called the nuclear envelope

• has nuclear pores → mRNA and ribosomes leave

• Contains chromatins → condenses into chromosomes during prophase

• Contains nucleolus → where ribosomes are produced (dark circle in the nucleus)

What is the structure of the mitochondria

• Has a double membrane → inner membrane is highly folded to form cristae → where aerobic respiration occurs to produce ATP → folded to increase SA : V ratio → increases ROR

• has its own DNA

What is the structure of the ribosome

• Found as free organelles in the cytoplasm or attached to the rough endoplasmic reticulum

• Involved in protein synthesis

What is the structure of the endoplasmic reticulum (rough and smooth)

• Rough → covered in ribosomes → polypeptide chain passes thru the rough endoplasmic reticulum to be folded into its 3D structure

  • Located close to the nucleus so mRNA can attach to the ribosomes

• Smooth → involved in production of lipids, carbs

What is the structure of the golgi apparatus

• Consists of flattened sacs of membrane → looks like a wifi symbol

• Modifies proteins and lipids before packing them into vesicles to be transported → exocytosis → protein is transported out of the cell

What is the structure of the lysosome

• Specialist form of a vesicle → contains digestive enzymes that breaks down waste products such as worn out organelles

What is the structure of the Centriole

• Centrosomes contain centrioles

• Hollow tubes made of microtubules

• During anaphase, centrioles release spindle fibres which pull a chromatid from each chromosome to opposite poles of the cell

• Each animal cell has 2 centrioles

Process of protein synthesis involving the cell ultrastructure

1. Nucleolus produces ribosomes for protein synthesis

2. Nucleus manufactures mRNA which is needed by ribosomes to make proteins

3. mRNA binds to ribosomes on the rough endoplasmic reticulum to make the polypeptide chain

4. Polypeptide chain passes thru the rough endoplasmic reticulum which folds it into its 3D structure

5. Transported to the golgi apparatus in vesicles

6. Golgi apparatus modifies the protein and packages it into a vesicle which buds off the golgi apparatus

What is a tissue

• A group of similar specialised cells working tg to perform a particular function

What is an organ

A group of specialised tissues working together to perform a particular function

What is an organ system

A group of specialised organs working together to perform a particular function

Formula for magnification

Image/actual

What is the process of the cell cycle

• Interphase

• Mitosis

• Cytokinesis

What are the stages of interphase

1. G1 phase → cell makes the RNA, enzymes and other proteins for growth

2. Synthesis phase → DNA is replicated → each chromatid is replicated causing chromosomes with 2 identical chromatids joined at the centromere to form

3. G2 phase → cell continues to grow, new DNA is checked for errors

Describe the process of mitosis (PMAT)

Prophase

• Chromosomes condense and are visible

• The 2 Centrosomes go to opposite poles of the cell → contains centrioles which produce spindle fibres

• Nuclear membrane breaks down

Metaphase

• Chromosomes line up at the equator of the cell

• Spindle fibres attach to the centromeres of each chromosome and each sister chromatid is attached to spindle fibres from opposite poles

Anaphase

• Centromere breaks in half and each sister chromatid is pulled to opposite poles of the cell by the spindle fibres

Telophase

• Chromatids reach opposite poles of the cell and decondense → now called chromosomes again

• Nuclear envelope reforms around each group of chromosomes

• Spindle fibres break down

What occurs in cytokinesis

• Once the nucleus has divided into 2 genetically identical nuclei → cell splits into 2 genetically identical daughter cells

What is mitosis important

• Growth of multicellular organisms

• Replacement of damaged cells

• Asexual reproduction → only 1 organism is needed