AS and A Level Biology 3 Views 1 Answers
Outline the need for energy in living organisms, as illustrated by active transport, movement and anabolic reactions, such as those occurring in DNA replication and protein synthesis
Outline the need for energy in living organisms, as illustrated by active transport, movement and anabolic reactions, such as those occurring in DNA replication and protein synthesis
Answer
Energy is essential for all living organisms to sustain life processes, and it plays a crucial role in a range of biological activities, including active transport, movement, and anabolic reactions. Here’s how energy is used in each context:
1. Active Transport
- Active transport is the movement of molecules or ions across cell membranes against their concentration gradient (from low to high concentration). Unlike passive transport, active transport requires energy in the form of ATP (adenosine triphosphate) because it moves substances against the natural direction of diffusion.
- Examples include the sodium-potassium pump, which maintains cellular ion balance essential for nerve transmission, muscle contraction, and overall cell function.
2. Movement
- Movement in living organisms, especially in animals, requires energy to power muscle contractions, cellular motility, and the beating of cilia and flagella. This movement is essential for various processes like locomotion, food acquisition, and circulation.
- Energy in the form of ATP fuels the sliding of actin and myosin filaments in muscle cells, allowing muscles to contract and relax. Even at the cellular level, energy is needed for cytoplasmic streaming, which moves materials within cells.
3. Anabolic Reactions
- DNA Replication: During cell division, cells must replicate their DNA, a process that requires significant energy. DNA replication involves the synthesis of new DNA strands using enzymes like DNA polymerase, which needs ATP to link nucleotides together.
- Protein Synthesis: The synthesis of proteins from amino acids (an anabolic reaction) requires energy. The process involves transcription (copying DNA to RNA) and translation (assembling amino acids into proteins), with ribosomes requiring ATP and GTP to link amino acids via peptide bonds.
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