Questions and Answers
How many chromosomes do we have?
46 chromosomes: 44 autosomes and 2 sex chromosomes
What are homologous chromosomes?
Pairs of autosomes, one from each parent, having the same genes in the same order.
What is fertilization?
The process where egg and sperm cells join to form a zygote with 46 chromosomes.
What is mitosis?
Signup and view all the answers
What is meiosis?
Signup and view all the answers
What does 'too many or too few' refer to in terms of chromosomes?
Signup and view all the answers
What are missing pieces in chromosomes?
Signup and view all the answers
Study Notes
Human Chromosome Count
- Humans have 46 chromosomes: 44 autosomes (22 pairs) and 2 sex chromosomes (XX for female, XY for male).
Homologous Chromosomes
- Autosomal pairs, known as homologous chromosomes, consist of one chromosome from each parent.
- Homologous chromosomes share the same genes in the same sequence but may have different DNA sequences.
Fertilization Process
- Egg and sperm cells each contain 23 chromosomes, half of the full count in regular cells.
- Fertilization combines an egg and sperm to create a zygote with 46 chromosomes.
Mitosis Overview
- The zygote first replicates each chromosome into identical copies called sister chromatids.
- During division, each new cell receives one copy of each chromosome, continuing the process to develop a full organism through mitosis.
Meiosis Explained
- Meiosis is a specialized division for forming egg and sperm cells, reducing chromosome number by half while enhancing genetic diversity.
- In meiosis, homologous chromosomes pair, exchange genetic material (recombination), and ultimately produce four unique daughter cells, each with 23 chromosomes.
Nondisjunction Consequences
- Nondisjunction is an error during meiosis, leading to uneven distribution of chromosomes.
- Resulting zygotes may exhibit trisomy (three copies of a chromosome) or monosomy (missing a chromosome).
- Autosomal trisomy and monosomy are often lethal, while most sex chromosome anomalies allow for survival and health.
Chromosomal Deletions
- Chromosomal segments may be lost or rearranged during meiosis, affecting genetic material.
- Deletions may be terminal (at chromosome ends) or interstitial (internal breakage followed by loss).
- Large deletions can result in genetic disorders, depending on missing gene functions, with smaller deletions often undetectable on karyotypes.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Dive into the fascinating world of chromosomes with these flashcards. Learn about the number of chromosomes in a human cell and the concept of homologous chromosomes. Perfect for students studying biology or genetics.
