grade 12 biology

PDF 137 стр. 10,4 МБ Бесплатная загрузка

137 стр.

FaylHub.uz

Скачать через Telegram

Размер 10,4 МБ

Тип файла PDF

Страницы 137

Обновлено Дек 2025

Предварительный просмотр (5 стр.)

Прокрутите вниз 👇

1 / 137

unit 4 genetics grade 12 biology unit 2 microorganisms by ebisa geleta what are microorganisms? microorganisms question: what are micro-organism (also called microbes)?  are microscopic organisms that cannot be seen with the naked eyes.  it needs a tool called microscope most of them are unicellular  some are multicellular ( ex, those which can photosynthesize their food) cont…  the branch of science that used to study about microorganisms know as microbiology.  microbiology study:  what they are  how they work and  what they do. note: microorganisms are everywhere  based on evolutionary lines, there are three main kinds of organisms.  these are: 1. bacteria 2. archaea and 3. eukarea note: archaea have cell walls without peptidoglycan, while bacterial cell walls contain peptidoglycan eubacteria • eubacteria: literally means "true bacteria“ • bacteria are relatively simple in structure. • they are prokaryotic unicellular organisms with …

2 / 137

t encloses the cell's nucleus, and nucleolus). g) they lack: mitochondria, golgi apparatus, plastid and endoplasmic reticulum. h) both dna and rna are present in the bacterial cell. structure of bacterial cell  as bacterial cells are very minute (very small), they are studied under electron microscope in which it reveals various structures.  some of these are external to the cell wall while  other are internal to the cell wall.  the brief descriptions of the readily evident structures of bacteria is as follows: pili: they initiate contacts between mating pairs; or they facilitate the transfer of genetic material; cytoplasm: transport, biosynthesis nucleoid: regulates the growth, reproduction, and function of the prokaryotic plasmid: communication of genetic information between bacteria  eukaryotic microbes are an extraordinarily diverse group, including species with a wide range of:  life cycles,  morphological specializations, and  nutritional needs. • although more diseases …

3 / 137

aggregates (a feature of tissue formation that allows the binding of cells of the same), motility, formation of spores, and reaction to the gram stain • in general the way that bacteria can be classified include; 1. shape i. cocci ii. bacilli iii. spirochaetes iv. comma 2. cell wall composition i. gram positive ii. garm negative 3. respiration mode i. aerobic bacteria: require oxygen for respiration. examples: pseudomonas and escherichia coli. ii. anaerobic bacteria: do not require oxygen for respiration. they use alternative electron acceptors such as nitrate, sulfate, or carbon dioxide. • anaerobic bacteria can be further divided into two subcategories: a) facultative anaerobes: these bacteria can switch between aerobic and anaerobic respiration depending on the availability of oxygen. examples: include escherichia coli and staphylococcus aureus. • b) obligate anaerobes: these bacteria are unable to survive in the presence of oxygen, and they rely on anaerobic respiration exclusively. examples: …

4 / 137

planes and remain in a group of four, 4. sarcinae: those that divide into three planes and remain attached in cube-like groups of eight. 5. staphylococci: when the bacteria's divide into multiple planes to form clusters or broad sheet-like arrangements. 2. bacilli (singular, bacillus) - rod-shaped bacteria  bacilli are not arranged in complex patterns as compared to coccus  most bacilli occur in pairs and are called diplobacilli.  but some species also occur in chain-like forms called streptobacilli, example : subtilis (not a frank human pathogen but can cause toxin to human ) anthracis (anthrax disease) 3. spirochaetes - spiral or corkscrew-shaped bacteria (syphilis)  spirilla are helically spiral-shaped bacteria.  they have one or more twists and are never straight.  they are basically rods with helical curves like a corkscrew and have fairly rigid bodies. 4. comma-vibrio cholera (vibrio cholerae)  vibrio cholerae is a bacterium …

5 / 137

he gram staining process includes four basic steps, including: 1. heat fix/ attach the bacteria to the silde, 2. applying a primary stain (crystal violet), 3. adding a mordant (gram's iodine), 4. rapid decolorization with ethanol, acetone or a mixture of both, & 5. counterstaining with safranin. note: then observe the color change at each levels. the staining technique includes simple staining (use single dye) or differencial staining (use different dyies) key words a) gram's staining: a test for distinguishing bacteria. named after hans christian gram, who developed the technique in 1884) b) differential staining: is a staining procedure that distinguishes organisms based on their staining properties. peptidoglycan: the rigid layer of the cell walls of bacteria, a thin sheet composed of n-acetylglucosamine, n-acetylmuramic acid, and a few amino acids. endotoxin: the lipopolysaccharide portion of the cell envelope of certain gram-negative bacteria, which is toxin to human when solubilized. nutritional …

Хотите читать дальше?

Скачайте все 137 страниц бесплатно через Telegram.

Скачать полный файл

О "grade 12 biology"

unit 4 genetics grade 12 biology unit 2 microorganisms by ebisa geleta what are microorganisms? microorganisms question: what are micro-organism (also called microbes)?  are microscopic organisms that cannot be seen with the naked eyes.  it needs a tool called microscope most of them are unicellular  some are multicellular ( ex, those which can photosynthesize their food) cont…  the branch of science that used to study about microorganisms know as microbiology.  microbiology study:  what they are  how they work and  what they do. note: microorganisms are everywhere  based on evolutionary lines, there are three main kinds of organisms.  these are: 1. bacteria 2. archaea and 3. eukarea note: archaea have cell …

Этот файл содержит 137 стр. в формате PDF (10,4 МБ). Чтобы скачать "grade 12 biology", нажмите кнопку Telegram слева.

Теги: grade 12 biology PDF 137 стр. Бесплатная загрузка Telegram