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molecules that make up cells
The second unit of Biology Compulsory Course has summarized and organized the knowledge points, covering all core contents, which is very convenient for everyone to learn. Suitable for exam review and preview to improve learning efficiency. Hurry up and collect it to learn together!
Edited at 2024-11-30 22:38:36- Recommended to you
- Outline
molecules that make up cells
elements and compounds in cells
elements that make up cells
Lots of elements
C,H,O,N,P,S,K,Ca,Mg
trace elements
Fe,Mn,Zn,Cu,B,Mo
The various elements that make up cells mostly exist in the form of compounds
compounds that make up cells
organic matter
Protein (7%~10%)
Lipids (1%~2%)
Sugars and nucleic acids (1%~1.5%)
Inorganic matter
Water (70%~90%)
Inorganic salt (1%~1.5%)
Detection of carbohydrates, fats and proteins in biological tissues
Carbohydrates: Fehling's reagent
Liquid A: 01g/ml NaOH solution
Liquid B: 0.05g/ml CuSO₄ solution
Water bath heating 50℃~65℃ 2min
Mix equal parts ready for use
Formation of brick red precipitate
Fat: Sudan III dye
Wash away the floating color with 50% alcohol solution by volume
Sudan III dye is easily soluble in alcohol solution with a volume fraction of 50%
Observe orange fat particles under low magnification
Protein: Biuret reagent
Solution A: 0.1g/ml NaOH solution
Liquid B: 0.01g/ml CuSO₄ solution
Ready for use, add drops in sequence
First add 1ml of solution A to provide an alkaline environment
Add another 4 drops of solution B
A purple reaction occurs
inorganic substances in cells
water in cells
Free water: exists in a free state, can flow freely, and accounts for more than 95.5% of all water in cells.
Easy to flow and easy to evaporate
Loss of free water when dried
effect
good intracellular solvent
Water is a polar molecule. Positively or negatively charged molecules or ions readily bind to water.
Participate in biochemical reactions within cells
Transport of nutrients and metabolism
Provides a liquid environment for cell life and maintains cell shape
Bound water: Combined with other substances in cells (proteins, polysaccharides, etc.), accounting for about 4.5% of all water in cells, becoming a constituent cost of organisms
Not easy to flow and not easy to lose
Loss of bound water during drying
Role: an important component of cell structure
Under certain conditions, free water and bound water can transform into each other.
Cooling: free water → bound water (warming and vice versa)
Free water → bound water (life activities slow down, metabolism slows down)
Bound water → free water (strong life activities and accelerated metabolism)
Free water/bound water↑strong cell metabolism and weak stress resistance
Free water/bound water↓Slow cell metabolism and strong stress resistance
Has a high specific heat capacity
When the oxygen end of one water molecule is close to the hydrogen end of another water molecule, the electrostatic attraction between them forms a weak attraction - a hydrogen bond.
The temperature of water is relatively difficult to change
Very important for maintaining the stability of life systems
Able to maintain liquid state at room temperature and have fluidity
Hydrogen bonds are weak, easily broken, and can only last for a very short time. Hydrogen bonds are constantly broken and formed.
inorganic salts in cells
Most inorganic salts in cells exist in ionic form
effect
Important component of complex intracellular compounds
Maintain normal life activities of cells and organisms
Maintain cell acid-base balance
Maintain osmotic pressure balance inside and outside cells
Sugars and lipids in cells
sugars in cells
Generally composed of three elements, C H O
Carbohydrates abbreviated as CH₂O
Sugar is an important energy substance
Monosaccharides (all reducing sugars)
Five-carbon sugar (cannot be oxidized to provide energy)
Ribose
Cells contain RNA components
deoxyribose
Cells contain DNA components
six carbon sugar
glucose
found in cells
Main energy substance "dye of life"
First used by cells
stored by cells when in surplus
Synthesize glycogen
Convert to fat (can be converted in large amounts)
fructose
in plant cells
energy supply
galactose
in animal cells
energy supply
disaccharide
Maltose (reducing sugar)
two molecules of glucose
Rich in sprouted wheat grains
Sucrose (non-reducing sugar)
One molecule of glucose One molecule of fructose
sugar cane beet
Lactose (reducing sugar)
One molecule of glucose One molecule of galactose
human and animal milk
Polysaccharides (all non-reducing sugars)
starch
The basic unit is glucose
Energy storage substances in plants
Food crops: seeds of corn, wheat, rice, potatoes, yams, sweet potatoes and other plants, abnormal stems or roots, and the fruits of some plants
glycogen
The basic unit is glucose
energy storage substance of animal cells
Hepatic glycogen (in the liver)
Supplement blood sugar (glucose)
Muscle glycogen (in muscles)
Only supplies energy to muscles
cellulose
The basic unit is glucose
main component of cell wall
difficult to digest
Promote gastrointestinal motility, reduce the risk of colorectal cancer, help maintain cardiovascular and cerebrovascular health, and prevent diabetes...
Chitin (chitin)
The basic unit is N-acetylglucosamine
crustacean insect exoskeleton
Can effectively combine with heavy metal ions in solution and can be used for wastewater treatment
Can be used to make food packaging paper and food additives
Can be used to make artificial skin
Composition elements: CH O N
lipids in cells
The main constituent elements are C H O and some also contain N P
Compared with sugars, the H content is higher and the O content is much lower than sugars.
Usually insoluble in water but soluble in fat-soluble organic solvents (eg. acetone, chloroform, ether)
Fat
One molecule of glycerol, three molecules of fatty acid → triacylglycerol (triglyceride)
effect
Good energy storage substance in cells
Good thermal insulator plays the role of heat preservation
Has a buffering and decompression effect and can protect internal organs
Fat is generally only broken down to provide energy when carbohydrates are insufficient and cannot be converted into carbohydrates in large quantities.
Phospholipids
One hydroxyl group of glycerol is combined with phosphoric acid and its derivatives (C H O N P)
Mainly distributed in the brains, egg cells, livers and soybean seeds of humans and animals
It is an important component of cell membranes and various organelle membranes.
sterol
cholesterol
Can be converted into vitamin D
An important component of animal cell membranes
Participates in the transport of lipids in the blood in the human body
sex hormones
Promote the development of human and animal reproductive organs and the formation of germ cells
stimulate and maintain secondary sexual characteristics
Vitamin D
Effectively promotes the absorption of calcium and phosphorus in the intestinal tract of humans and animals
Protein is the main carrier of life activities
protein function
Structural proteins: important proteins that make up the structure of cells and organisms
Catalysis: Chemical reactions in cells are inseparable from enzymes. Most enzymes are proteins, and a few enzymes are RNA.
Transport function: e.g. hemoglobin carrier protein
Regulating (information transmission) role: Some proteins play the role of information transmission and can regulate the body's life activities, such as insulin and growth hormone.
Immunity: eg. Antibodies are proteins that can help the body resist viruses, bacteria and other antigens.
The basic building blocks of protein – amino acids
General structural formula: (C₂H₄O₂N–R)
The difference between amino acids is the difference in the R group
Side chain groups determine the type and physical and chemical properties of amino acids
Composition elements: C H O N, some also contain S
There are 21 types of amino acids that make up human proteins.
Essential Amino Acids (8)
Lysine
Tryptophan
Phenylalanine
Methionine
threonine
Isoleucine
Leucine
valine
Non-essential amino acids (13)
protein structure
Amino acids condense through dehydration to form peptide chains
Dehydration condensation: The carboxyl group of one amino acid molecule is connected to the amino group of another amino acid molecule, and a molecule of water is removed at the same time.
The chemical bond that connects two amino acid molecules is called a peptide bond
Compounds formed by the condensation of multiple amino acids and containing multiple peptide bonds are called polypeptides
Because hydrogen bonds can be formed between different amino acids on the peptide chain, the peptide chain can twist and fold to form a protein molecule with a certain spatial structure.
protein diversity
Amino acid level
Different types of amino acids
Different amounts of amino acids
Amino acids are arranged in different order
Peptide chain level
The way polypeptide chains twist and fold and the spatial structures they form vary widely.
transsexual
Irreversible
Over-acidity, over-alkali, high temperature, and alcohol will all cause protein denaturation.
The spatial structure is destroyed, the physical and chemical properties are changed, and the biological activity is lost.
No disruption of the peptide chain is involved, the primary structure remains intact
Salting out & hydrolysis
Salting out
Physical changes are recoverable
Does not affect protein properties
hydrolysis
peptide bond cleavage
Proteins can be broken down into short peptides or amino acids
Nucleic acids are carriers of genetic information
Types of nucleic acids and their distribution
deoxyribonucleic acid (DNA)
Mainly distributed in the nuclei of eukaryotic cells & nucleoids of prokaryotic cells
Mitochondria and chloroplasts also contain small amounts of
Ribonucleic acid (RNA)
Mainly distributed in the cytoplasm
Small amount in cell nucleus
Nucleic acids are long chains of condensed nucleotides
Basic unit - nucleotide
Nucleotide: one molecule of five-carbon sugar, one molecule of phosphate, one molecule of nitrogenous base
DNA: Deoxyribonucleotide
Five-carbon sugar: deoxyribose
Nitrogenous base
T: Thymine (specific)
A: Adenine
G: guanine
C: Cytosine
RNA: Ribonucleotide
Five-carbon sugar: ribose
Nitrogenous base
U: Uracil (specific)
A: Adenine
G: guanine
C: Cytosine
DNA is a long chain of deoxyribonucleotides linked together
Made up of two deoxyribonucleotide chains
characteristic
Diversity
The number of deoxynucleotides is large and the order is diverse
specificity
The sequence of DNA deoxynucleotides is unique to each individual
stability
Internal bases complement each other
regular double helix structure
Carbon is the core element of life. Without carbon, there would be no life.
RNA is a long chain of ribonucleotides linked together
Made up of a chain of ribonucleotides
Function
is the substance that carries genetic information within cells
It plays an extremely important role in the genetic variation of organisms and protein biosynthesis.
Biological macromolecules use carbon chains as skeletons
biological macromolecules
polysaccharide
protein
nucleic acid
monomer
The basic unit of biological macromolecules
Each monomer has a carbon chain composed of several adjacent carbon atoms as a backbone.
multimer
Biological macromolecules are polymers composed of many monomers linked together