National 5 Biology Unit 1 Cell Biology Chapter

National 5 Biology Unit 1: Cell Biology Chapter 1: Cell Structure 10/15/2021 Mrs Smith 1

National 5 Biology Learning Intentions By the end of this chapter, you should be able to describe cell structure - Specifically be able to discuss - Cell ultrastructure and functions to include: cell wall, mitochondrion, chloroplast, cell membrane, cytoplasm, vacuole, nucleus, ribosome and plasmid. - You should also be able to describe the ultrastructure by using examples from typical plant, animal, fungi and bacterial cells. - Explain fungal structure in terms of similarity to plant and animal cells but with a different cell wall structure. (Cell wall structure in fungal and bacterial cells is different from plant cells, ie chitin not cellulose) - Bacterial structure description should include the absence of organelles (no nucleus, mitochondria vacuole or chloroplasts) and a different cell wall structure to plant and fungal cells. -Bacterial structure should also include a description of there chromosomes and plasmid. 10/15/2021 Mrs Smith 2

CELLS ARE THE STARTING POINT! • All living organisms on Earth are divided into cells. The main concept of cell theory is that cells are the basic structural unit for all organisms. Nothing smaller than a cell can lead to independent life. • Cells are small compartments that hold the biological equipment necessary to keep an organism alive and successful. Living things may be single-celled or they may be very complex such as a human being. 10/15/2021 Mrs Smith 3

Plant Cells – Can be viewed under the microscope • Below are examples of plant cells viewed under the microscope • Some of a plant cells parts can be seen clearly when mounted in water (see below) • Other cell structures that are not so obvious can often be shown up more clearly by the addition of a STAIN (dye). Iodine solution can be used on onion cells to stain the nuclei. Elodea leaf cells in water 10/15/2021 Mrs Smith Onion leaf cells in iodine solution 4

Using stains with the microscope. Stains can be used to make cells more visible under the microscope, e. g. Iodine solution. Onion skin: 2 pieces were taken from the bottom layer of an onion and placed on 2 different slides. With one, some iodine was placed n the slide to see the different layers, The other slide was left unstained. 10/15/2021 Mrs Smith 5

Onion Cell Lab Instructions. • Add 2 drops of iodine to the centre of a glass slide. Be careful! Iodine can stain your clothes. • Take a small piece of onion. Use tweezers to peel off the skin from the underside (the rough, white side) of the onion. Throw the rest of the onion piece away. • Carefully lay the onion skin flat in the centre of the slide on top of the iodine. • Add 2 drops of iodine to the top of the onion skin. • Stand a thin glass cover slip on its edge near the onion skin, next to the drop of iodine. • Slowly lower the other side of the cover slip until it covers the onion skin completely. If there air bubbles, gently tap on the glass to “chase” them out. 10/15/2021 Mrs Smith 6

Draw what you see. Iodine Solution with air bubbles Why are there no chloroplasts in onion cells? Chloroplasts are absent from onion skin cells because it grows underground in the darkness (so what would be the point? ) 10/15/2021 Mrs Smith 7

This is what our Onion cell looked like! 10/15/2021 Mrs Smith 8

Plant Cell (Pond weed). Lab Instructions • Tear off one small leaf/stem from the plants in the fish tank. • Add one drop of tap water to the slide. • Stand a thin glass cover slip on its edge near the leaf, next to the drop of water. • Slowly lower the other side of the cover slip until it covers the leaf completely. Make sure there are no air bubbles. 10/15/2021 Mrs Smith 9

Draw what you see. 10/15/2021 Mrs Smith 10

While some cells do look different, all cells have these three basic features. nucleus cytoplasm cell membrane 10/15/2021 Mrs Smith 11

The Nucleus Controls the cell’s activities Controls all the chemical reactions inside the cell 10/15/2021 Mrs Smith 12

The Cell Membrane The cell membrane is selectively permeable and controls what substances may enter and leave the cell. 10/15/2021 Mrs Smith Cell membrane 13

The Cytoplasm It is a jelly like material All the chemical reactions taking place in the cell occur here 10/15/2021 Mrs Smith 14

ORGANELLES - Continued • Organelles are tiny structures (such as chloroplasts) that are: – Present in a cells cytoplasm as discrete units normally surrounded by a membrane. – Responsible for a specialised function (such as photosynthesis 10/15/2021 Mrs Smith 15

Ultrastructure • Cell structure is actually way more complicated than we have been teaching you…… • There are even smaller structures in a cell. These minute structures cannot be seen with a normal light microscope. They can only bee seen using a more sophisticated piece of equipment called the electron microscope. 10/15/2021 Mrs Smith 16

Cooperative activity Cell race 20 minutes max! Your group will be issued with four different cell diagrams and four different descriptions as well as your own summary sheet. 1. Read each description carefully. 2. Match up each description with the correct cell. 3. Copy each cell picture into your jotter 4. Using all of the descriptions complete your table with a general function for each of the cell parts you have identified. 5. Complete the table by stating which of the cell parts are present in each cell type. You have finished the cell race only when every member of the group has completed their own diagram and table and this has been checked by your teacher so assign group tasks wisely and remember to include everybody. 10/15/2021 Mrs Smith 17

Animal Cell Animal cells are bounded by a cell membrane that controls entry and exit of substances. The cytoplasm is the “factory” part of the animal cell in which chemical reactions take place to manufacture various substances. The nucleus holds the DNA molecules (chromosomes) that are composed of sections called genes. Gene code for the making of proteins that control the activity of the cell. Embedded in the cytoplasm are mitochondria- sausage shaped structures with a smooth outer membrane and a folded inner membrane. It is in the mitochondria that aerobic respiration (respiration that uses oxygen) takes place. Also in the cytoplasm of animal cells free or attached to membranes are ribosomes- small spherical structures that are where protein molecules are created using instructions supplied from the DNA in the nucleus. 10/15/2021 Mrs Smith 18

Plant Cell Plant cells are bounded by a cell wall made of cellulose fibres that forms a rigid box that although permeable to all but the largest molecules provides support for the cell and the plant as a whole. To the inside of the cell wall is the cell membrane that controls entry and exit of substances and is composed of proteins and phospholipids. The cytoplasm is the “factory” part of the plant cell in which chemical reactions take place to manufacture various substances. The nucleus holds the DNA molecules (chromosomes) that are composed of sections called genes. Genes code for the making of proteins that control the activity of the cell. Embedded in the cytoplasm are mitochondriasausage shaped structures with a smooth outer membrane and a folded inner membrane. It is in the mitochondria that aerobic respiration (respiration that uses oxygen) takes place. Also in the cytoplasm of plant cells free or attached to membranes are ribosomes- small spherical structures that are where protein molecules are created using instructions supplied from the DNA in the nucleus. Chloroplasts are the site of photosynthesis in green plant cells. Vacuoles are fluid filled sac containing cell sap which are important in controlling water balance within the cell. 10/15/2021 Mrs Smith 19

Fungal Cell Fungal cells are bounded by a cell wall made of chitin that forms a rigid box that provides support for the cell. To the inside of the cell wall is the cell membrane that controls entry and exit of substances and is composed of proteins and phospholipids. The cytoplasm is the “factory” part of the fungal cell in which chemical reactions take place to manufacture various substances. The nucleus is the control centre of the cell. It holds the DNA molecules (chromosomes) that are composed of sections called genes. Gene codes for the making of proteins that control the activity of the cell. Embedded in the cytoplasm are mitochondria- sausage shaped structures with a smooth outer membrane and a folded inner membrane. It is in the mitochondria that aerobic respiration (respiration that uses oxygen) takes place. Also in the cytoplasm of fungal cells free or attached to membranes are ribosomessmall spherical structures that are where protein molecules are created using instructions supplied from the DNA in the nucleus. Vacuoles are fluid filled sac containing cell sap which are important in controlling water balance within the cell. 10/15/2021 Mrs Smith 20

Bacterial Cell Bacterial cells are bounded by a cell wall made of peptidoglycan that forms a rigid box that provides support for the cell. To the inside of the cell wall is the cell membrane that controls entry and exit of substances and is composed of proteins and phospholipids. The cytoplasm is the “factory” part of the bacterial cell in which chemical reactions take place to manufacture various substances. In a bacterial cell the DNA is free in the cytoplasm usually in one large mass. The DNA is composed of sections called genes. Genes code for the making of proteins that control the activity of the cell. In bacterial cells smaller circles of DNA called plasmids are found. Plasmids are freely exchanged between bacterial cells and are now used in “genetic engineering”. Also free in the cytoplasm of bacterial cells are ribosomes- structures that are where protein molecules are created using instructions supplied from the DNA. 10/15/2021 Mrs Smith 21

Structure Function In animal cell? In plant cell? In fungal cell? In bacterial cell? cell membrane Holds cell contents and controls entry and exit of substances. Yes Yes cytoplasm Cell’s “factory” –chemical reactions occur here. Yes Yes Contains DNA which holds the information to make proteins which control the activity of the cell. Yes Yes Yes No Yescellulose Yeschitin No Yes nucleus mitochondrion ribosome cell wall vacuole chloroplast plasmid 10/15/2021 Site of aerobic respiration. Manufacture of protein using instructions from DNA. Rigid box gives organism support. Fluid filled sac Site of photosynthesis where carbohydrate is made. Ring of DNA exchanged readily between cells. Mrs Smith No Yes No No Yespeptidoglycan No No Yes 22

Cells have differences in structure • Close examination of 4 types of cells sown below show they have some features in common but also differ from one another in other ways. 10/15/2021 Mrs Smith 23

Animal Cell Structure 10/15/2021 Mrs Smith 24

Animal Cell Structure 10/15/2021 Mrs Smith 25

Example animal cells nerve cell 10/15/2021 ciliated epithelial cells blood cells sperm and egg cells Mrs Smith 26

Plant Cell Ultrastructure Cellulose 10/15/2021 Mrs Smith 27

Plant Cell Structure THEY ALSO HAVE MITOCHONDRIA AND RIBOSOMES 10/15/2021 Mrs Smith 28

Example Plant Cells root hair cells onion epidermal cells 10/15/2021 leaf cells Mrs Smith xylem cells phloem cells 29

Fungal Cell Ultrastructure chitin 10/15/2021 Mrs Smith 30

Fungal Cell Ultrastructure 10/15/2021 Mrs Smith 31

Example fungal Cells yeast cells mushroom mycelial cells. Mrs Smith 10/15/2021 Penicillium notatum 32 Fusarium mycelial cells

Bacterial Cell Ultrastructure Peptoglycan 10/15/2021 Mrs Smith 33

Bacterial Cell Ultrastructure 10/15/2021 Mrs Smith 34

Example Bacterial Cells Eschericia coli 10/15/2021 Rhizobium Mrs Smith Cholera bacteria 35

Cell Rap 10/15/2021 Mrs Smith 36

The Cell Song 10/15/2021 Mrs Smith 37

Cell Structure Notes cells All living things are composed of one or more _______ , the basic unit of life. The cells of green plants, animals and fungi have several structures in nucleus common, including a ____, and mitochondria. Bacterial ______ cells lack a cell wall and store genetic material within plasmids _____. chloroplasts but all cells contain Only green plants contain _____, ribosomes, a cell membrane and cytoplasm. The cell’s activities are controlled by the nucleus. A plant cell is supported by the cell wall and its cell _____ sap is stored in its _____ vacuole. Bacterial 10/15/2021 Cells Plasmids Supported Chloroplasts Mrs Smith Nucleus Sap 38

Activity – Measuring cell sizes • Cells cannot be seen without the aid of a microscope. • They are so small that we used units called micrometers (μm) or microns to measure them • There are 1000 microns in 1 millimetre. 10/15/2021 YOU MUST BE ABLE TO MOVE BETWEEN THESE DIFFERENT UNITS> MAKE SURE YOU PRACTISE CONVERTING ONE TO Mrs Smith THE OTHER. 39

Measuring cell sizes We can estimate the sizes of cells by knowing the diameter of the field of view. e. g. If the field of view is 2 mm which is 2000μm and there are 8 cells streching from one side to the other, then each cell must be 250μm (2000/8) 10/15/2021 Mrs Smith 40

Activity – Measuring cell sizes 2 mm (field of view)/ 5 (no. of cells lengthwise across field of view) = 0. 4 mm 2 mm (field of view)/ 10 (no. of cells up and down in field of view) = 0. 2 mm 0. 4 10/15/2021 0. 2 Mrs Smith 41

Activity – Measuring cell sizes This cell is 25 mm in the diagram. What is the actual size of the cell? 10/15/2021 Mrs Smith 0. 0625 mm 42

Activity – Measuring cell sizes This cell is 20 mm in the diagram. What is the actual size of the cell? 10/15/2021 Mrs Smith 0. 05 mm 43

Task TYK • Complete questions 1 – 4. Torrance p 5 10/15/2021 Mrs Smith 44

Task TYK • Complete questions 1 – 4. Torrance p 5 1. 2. 2. 3. Cells (1) A) Cell membrane, mitochondria, nucleus, ribosome's. (4) B) Cell wall, chloroplasts, large central vacuole (3). Chloroplast for photosynthesis, nucleus for control of cell activities, cell membrane for control of movement of substances onto and out of cell, mitochondrion for aerobic respiration (4). 4. A) 1 millimetre = 1000 micrometers (1) 10/15/2021 Mrs Smith 45 4. B) 1 micrometer = 0. 001 millimetres (1).

Quick test 1. How is the cell wall of a plant cell different from that of a yeast cell? 2. Name two cell structures that cannot be seen with a light microscope. 3. What features do yeast and p[lant cells have in common? 10/15/2021 Mrs Smith 46

Answers 1. How is the cell wall of a plant cell different from that of a yeast cell? 1. Plant cell wall is made of cellulose, yeast cell wall is made of chitin. 2. Name two cell structures that cannot be seen with a light microscope. 2. Ribosomes and mitochondria. 3. What features do yeast and plant cells have in common? 3. Cell wall, nucleus, cytoplasm, cell membrane, ribosomes, mitochondria and vacuole. 10/15/2021 Mrs Smith 47

National 5 Biology Have we achieve our learning Intentions By the end of this chapter, you should be able to describe cell structure - Specifically be able to discuss - Cell ultrastructure and functions to include: cell wall, mitochondrion, chloroplast, cell membrane, cytoplasm, vacuole, nucleus, ribosome and plasmid. - You should also be able to describe the ultrastructure by using examples from typical plant, animal, fungi and bacterial cells. - Explain fungal structure in terms of similarity to plant and animal cells but with a different cell wall structure. (Cell wall structure in fungal and bacterial cells is different from plant cells, ie chitin not cellulose) - Bacterial structure description should include the absence of organelles (no nucleus, mitochondria vacuole or chloroplasts) and a different cell wall structure to plant and fungal cells. -Bacterial structure should also include a description of there chromosomes and plasmid. 10/15/2021 Mrs Smith 48