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ludmilkaskok [199]
3 years ago
5

What must happen before a chemical reaction can begin?

Biology
2 answers:
kykrilka [37]3 years ago
6 0
A energy barrier must be overcome.
bixtya [17]3 years ago
6 0

Answer:

Before a chemical reaction happens, what should happen is:

  • reagent contact,
  • chemical affinity,
  • favorable collisions, and
  • activation energy.

Explanation:

  • Contact between reagents: In order for the reactant molecules to collide with each other, they must come into contact. For example, sodium is a metal element that reacts with oxygen, oxidizing in minutes when in contact with air.
  • chemical Affinity: This property refers to the ability of one substance to react with another, because even if two or more substances are brought into contact but there is no affinity between them, the reaction will not occur
  • favorable collisions: For a chemical reaction to occur, the molecules of the reagents that came in contact must effectively collide. The greater the number of favorable collisions, the faster the chemical reaction will be.
  • Activation Energy: For collisions to be favorable and result in a chemical reaction, the reagents must have a minimum energy, which is the activation energy.  Activation energy is required for the formation of the activated complex, that is, an intermediate structure between reactants and products, where reactant bonds are being weakened and product bonds are being formed.
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Name the star closest to our solar system​
maksim [4K]

Answer:

See explanation below.

Explanation:

The star that is nearest to our solar system is Proxima Centauri. It is about 4.22 light years away. That means if you travel at the speed of light, it will take you 4.22 years to travel from here to there.

Hope this helps! Have an Awesome Day!! :-)

6 0
3 years ago
The _____ is very useful for examining live specimens found in drops of water or thin slices of tissue such as skin or muscle.
Scrat [10]
A. Compound Light Microscope
7 0
3 years ago
Based on the diagram shown above the Glycolsis, briefly describe the first step of cellular respiration, emphasizing the locatio
RSB [31]

Answer:

Glycolysis takes place in the cytosol which is part of the cytoplasm of the cell. Glucose is rearranged and phosphorylated to form F-1,6BP(fructose 16 bisphosphate which is very unstable) its splits into 2 phosphorylated 3C sugars (DHAP and G3P)(can interconvert) both form G3P to enter 3rd phase, G3P converted into pyruvate creates 4 ATP in total but has a net of 2 ATP and creates NADH. The raw materials needed are two molecules of NAD+ per glucose as well as 2 ATPs. Hope this helps!

Explanation:

3 0
3 years ago
All the offspring of a cross between a tall pea plant and a dwarf pea plant are tall. This means that the allele for tall plants
Olenka [21]

Answer:

All the offspring of a cross between a tall pea plant and a dwarf pea plant are tall. This means that the allele for tall plants is <u>DOMINANT OVER</u> the allele for dwarf plants.

Explanation:

Mendel's law of dominance state that the heterozygous genotype expresses only one allele of a gene out of the two alleles present together. The allele that is expressed in a heterozygous genotype is said to be the dominant one as it does not allow the expression of another allele of the gene.

The allele of a gene that is not expressed in the presence of its dominant allele is said to be the recessive one. Under such conditions, a heterozygous genotype expresses the dominant phenotype. When a tall and dwarf pea plants are crossed, all the F1 progeny is tall. This means that the allele for the tallness is dominant over the allele for the dwarfism.

7 0
4 years ago
PLEASE HELP, BIOLOGY!!!!
aliina [53]
Before DNA can be replicated, the double stranded molecule must be “unzipped” into two single strands. DNA has four bases called adenine (A), thymine (T), cytosine (C) and guanine (G) that form pairs between the two strands. Adenine only pairs with thymine and cytosine only binds with guanine. In order to unwind DNA, these interactions between base pairs must be broken. This is performed by an enzyme known as DNA helicase. DNA helicase disrupts the hydrogen bonding between base pairs to separate the strands into a Y shape known as the replication fork. This area will be the template for replication to begin.

Step 2: Primer Binding
The leading strand is the simplest to replicate. Once the DNA strands have been separated, a short piece of RNA called a primer binds to the 3' end of the strand. The primer always binds as the starting point for replication. Primers are generated by the enzyme DNA primase.

Step 3: Elongation
Enzymes known as DNA polymerases are responsible creating the new strand by a process called elongation. There are five different known types of DNA polymerases in bacteria and human cells. In bacteria such as E. coli, polymerase III is the main replication enzyme, while polymerase I, II, IV and V are responsible for error checking and repair. DNA polymerase III binds to the strand at the site of the primer and begins adding new base pairs complementary to the strand during replication. In eukaryotic cells, polymerases alpha, delta, and epsilon are the primary polymerases involved in DNA replication. Because replication proceeds in the 5' to 3' direction on the leading strand, the newly formed strand is continuous.

Step 4: Termination
Once both the continuous and discontinuous strands are formed, an enzyme called exonuclease removes all RNA primers from the original strands. These primers are then replaced with appropriate bases. Another exonuclease “proofreads” the newly formed DNA to check, remove and replace any errors. Another enzyme called DNA ligase joins Okazaki fragments together forming a single unified strand. The ends of the linear DNA present a problem as DNA polymerase can only add nucleotides in the 5′ to 3′ direction. The ends of the parent strands consist of repeated DNA sequences called telomeres. Telomeres act as protective caps at the end of chromosomes to prevent nearby chromosomes from fusing.

So if that here are the functions of enzymes used:
DNA helicase - unwinds and separates double stranded DNA as it moves along the DNA. It forms the replication fork by breaking hydrogen bonds between nucleotide pairs in DNA.
DNA primase - a type of RNA polymerase that generates RNA primers. Primers are short RNA molecules that act as templates for the starting point of DNA replication.
DNA polymerases - synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands.
Topoisomerase or DNA Gyrase - unwinds and rewinds DNA strands to prevent the DNA from becoming tangled or supercoiled.
Exonucleases - group of enzymes that remove nucleotide bases from the end of a DNA chain.
DNA ligase - joins DNA fragments together by forming phosphodiester bonds between nucleotides.

Have a nice day
4 0
3 years ago
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