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Chapter 9: Problem 14
Define the following terms: crossing over, synapsis, gamete, autosome,nondisjunction, and hom*ologous pair.
Short Answer
Expert verified
Crossing over: genetic exchange; Synapsis: chromosome pairing; Gamete: reproductive cell; Autosome: non-sex chromosome; Nondisjunction: improper chromosome separation; hom*ologous pair: chromosome pair.
Step by step solution
01
- Define Crossing Over
Crossing over is the process where hom*ologous chromosomes exchange segments of genetic material during meiosis. This leads to genetic recombination and contributes to genetic diversity in offspring.
02
- Define Synapsis
Synapsis is the pairing of two hom*ologous chromosomes during meiosis. This occurs during prophase I and is essential for the process of crossing over.
03
- Define Gamete
A gamete is a mature haploid reproductive cell that is involved in sexual reproduction. In humans, the male gamete is the sperm, and the female gamete is the egg.
04
- Define Autosome
An autosome is any chromosome that is not a sex chromosome. Humans have 22 pairs of autosomes and 1 pair of sex chromosomes.
05
- Define Nondisjunction
Nondisjunction is an error in meiosis or mitosis where chromosomes fail to separate properly, resulting in cells with an abnormal number of chromosomes. This can cause genetic disorders such as Down syndrome.
06
- Define hom*ologous Pair
A hom*ologous pair consists of two chromosomes, one from each parent, that are similar in shape, size, and genetic content. These pairs line up and synapse during meiosis.
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
crossing over
During meiosis, hom*ologous chromosomes exchange segments of genetic material in a process known as crossing over. This event happens during prophase I. As the chromosomes pair up closely, sections of their DNA are swapped.
This exchange leads to genetic recombination. As a result, the offspring get a mix of genes from both parents. This process increases genetic diversity, which is crucial for the evolution of species.
By combining genes in new ways, crossing over helps create new traits and variations that can be beneficial for survival.
synapsis
Synapsis is the pairing of two hom*ologous chromosomes during meiosis. This process occurs specifically during prophase I. The chromosomes line up side by side and become tightly connected.
This pairing is critical for crossing over to occur. Without synapsis, the hom*ologous chromosomes wouldn't be close enough for genetic material to be exchanged.
During synapsis, a protein structure called the synaptonemal complex forms between hom*ologous chromosomes, holding them together.
gamete
A gamete is a mature reproductive cell that carries half of the genetic information needed to create a new organism. There are two types of gametes: sperm in males and eggs in females. Both types are haploid, meaning they contain one set of chromosomes.
During fertilization, a sperm and an egg combine to form a zygote, which is diploid and has two sets of chromosomes.
The primary purpose of gametes is sexual reproduction, allowing genetic material from two parents to ensure variability in the offspring.
autosome
Autosomes are any chromosomes that are not sex chromosomes. Humans have a total of 22 pairs of autosomes.
These chromosomes carry the bulk of an individual's genetic information. They determine many traits and functions of the organism, excluding those directly related to sex.
The 23rd pair of chromosomes are the sex chromosomes, which determine an individual's sex.
nondisjunction
Nondisjunction is a mistake that can happen during cell division, either in meiosis or mitosis. During nondisjunction, chromosomes fail to separate properly.
This results in cells with an abnormal number of chromosomes, a condition known as aneuploidy.
Nondisjunction can lead to genetic disorders. For example, Down syndrome is caused by an extra copy of chromosome 21, a condition called trisomy 21.
hom*ologous pair
A hom*ologous pair consists of two chromosomes, one from each parent, that are similar in shape, size, and genetic content.
During meiosis, these pairs line up and synapse to prepare for crossing over.
hom*ologous pairs are essential for genetic variation and proper chromosome segregation. Each pair ensures that offspring receive a balanced set of genes from both parents.
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