Inheritance Flashcards
Inhetriance (26 cards)
What is inheritance (heredity)?
Transmission of traits from parents to offspring
Inheritance involves genetic information passed through generations.
Define genetics.
The scientific study of heredity and variation
Genetics examines how traits are passed and how they vary among individuals.
What do offspring inherit?
Genes, not physical traits directly
Genes encode the information that determines physical traits.
What are genes?
Segments of DNA located on chromosomes
Genes contain the instructions for making proteins that influence traits.
What are gametes?
Sperm and egg; vehicles of gene transmission
Gametes are haploid cells that combine during fertilization.
What is asexual reproduction?
Single parent produces genetically identical offspring (clones)
Asexual reproduction involves no fusion of gametes.
How do offspring arise in asexual reproduction?
Through mitosis
Asexual reproduction leads to clones of the parent organism.
What is genetic variation in asexual reproduction due to?
Mutations
Variations arise infrequently compared to sexual reproduction.
Give examples of organisms that reproduce asexually.
- Bacteria (binary fission)
- Yeast (budding)
- Hydra (budding)
- Strawberries (runners)
These organisms can reproduce without sexual reproduction.
What is sexual reproduction?
Two parents contribute genes to offspring
Sexual reproduction results in offspring with unique genetic combinations.
What processes are involved in sexual reproduction?
- Meiosis (gamete formation)
- Fertilization
These processes ensure genetic diversity in offspring.
What are somatic cells?
Body cells that are diploid (2n)
Somatic cells have two sets of chromosomes, one from each parent.
How many chromosomes do humans have?
46 chromosomes (23 pairs)
Chromosomes are paired as homologous chromosomes.
What are homologous chromosomes?
Chromosomes that have the same genes but different alleles
They pair up during meiosis.
What are gametes in terms of ploidy?
Haploid (n): One set of chromosomes
In humans, gametes contain 23 chromosomes.
What happens during fertilization?
Sperm (n) + Egg (n) → Zygote (2n)
Fertilization restores the diploid number in the zygote.
What is a karyotype?
Ordered display of chromosomes in a cell
Karyotypes can show chromosomal abnormalities.
What determines biological sex in humans?
Sex chromosomes: XX = female, XY = male
The 23rd pair of chromosomes are the sex chromosomes.
What are autosomes?
All other chromosomes (22 pairs in humans)
Autosomes do not determine sex.
Describe the human life cycle.
- Meiosis produces haploid gametes (n = 23)
- Fertilization forms a zygote (2n = 46)
- Mitosis & development form a multicellular organism
All somatic cells remain diploid.
What characterizes the animal life cycle?
Diploid organism (2n) produces haploid gametes (n) by meiosis
Only gametes are haploid; all other cells are diploid.
What is the alternation of generations in plants?
- Sporophyte (2n) produces spores (n) by meiosis
- Spores develop into a haploid gametophyte (n)
- Gametophyte produces gametes (n) by mitosis
- Gametes fuse to form a diploid zygote
The cycle continues with the sporophyte growing from the zygote.
What characterizes the fungal and protist life cycle?
Only the zygote is diploid (2n)
Meiosis immediately follows fertilization in this cycle.
What is the function of meiosis in sexual reproduction?
Reduces chromosome number by half (2n → n)
Meiosis ensures genetic diversity through various mechanisms.
