InheritanceEdexcel IGCSE Biology: Flashcards
Card 1 of 170 of 17 known
Question
What is the genome?
Tap or press Space to reveal
Tap card or press Space to flip
See all 17 cards
- What is the genome?
- The entire DNA of an organism.
- What is a gene?
- A section of DNA that codes for a specific protein.
- Describe the structure of DNA.
- Two strands coiled to form a double helix, linked by paired bases: adenine with thymine, and cytosine with guanine.
- How does RNA differ from DNA?
- RNA is single-stranded and contains uracil instead of thymine.
- What happens during transcription?
- In the nucleus, the DNA base sequence of a gene is copied into a strand of mRNA.
- What happens during translation?
- At a ribosome, tRNA molecules bring amino acids matching the mRNA codons (via their anticodons), joining them to build a protein.
- What is an allele?
- An alternative form of a gene.
- Define homozygous and heterozygous.
- Homozygous = two identical alleles for a gene; heterozygous = two different alleles for a gene.
- What is codominance?
- When both alleles in a heterozygous individual are expressed in the phenotype, with neither masking the other.
- What is polygenic inheritance?
- Inheritance of a characteristic controlled by many genes acting together, producing continuous variation.
- How is sex determined in humans?
- By one pair of chromosomes: XX produces a female, XY produces a male; sperm carry either an X or Y chromosome, eggs always carry X.
- What does mitosis produce, and when does it occur?
- Two genetically identical daughter cells; occurs during growth, repair, cloning and asexual reproduction.
- What does meiosis produce?
- Four genetically different haploid gametes, each with half the chromosome number.
- What are the diploid and haploid chromosome numbers in humans?
- Diploid = 46 (in body cells), haploid = 23 (in gametes).
- What is a mutation?
- A rare, random change in genetic material that can be inherited.
- What can increase the rate of mutation?
- Exposure to ionising radiation and certain chemical mutagens.
- Explain how antibiotic resistance spreads through a bacterial population.
- A random mutation gives some bacteria resistance; when antibiotic is used, resistant bacteria survive and reproduce while non-resistant bacteria die, increasing the proportion of resistant bacteria.