Cell Division & Genetics Chapter 19

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Questions and Answers

What is the primary function of chromosomes in cells?

To provide instructions for cellular functions (correct)

To store nutrients for the cell

To serve as a barrier against infections

To transport messages between cells

How many total chromosomes do tissue cells contain?

46 chromosomes (correct)

92 chromosomes

23 unique chromosomes

23 pairs of chromosomes

What is the primary role of mitosis in the human life cycle?

Generating unique genetic traits

Replacing old and damaged cells (correct)

Fusing sperm and egg nuclei

Creating gametes for reproduction

What distinguishes gametes from tissue cells in terms of chromosome number?

Gametes have 23 unique chromosomes and tissue cells have 46 total chromosomes Signup and view all the answers

How many chromosomes are present in the zygote after fertilization?

46 chromosomes Signup and view all the answers

What is a karyotype?

A profile showing an individual's chromosome arrangement Signup and view all the answers

What type of cells undergo mitotic division throughout adulthood?

Stem cells Signup and view all the answers

How many homologous chromosomes are present in tissue cells?

23 pairs Signup and view all the answers

What is created as a result of meiosis?

Gametes (sperm and egg) Signup and view all the answers

What is the significance of cell division in human life?

It is essential for reproduction, growth, and development Signup and view all the answers

During cell division, how must the chromosomes be prepared?

Each must be copied exactly Signup and view all the answers

Which chromosomes are categorized as sex chromosomes?

Chromosomes X and Y Signup and view all the answers

What happens to the original parent cell after mitosis?

It creates two genetically identical daughter cells Signup and view all the answers

How can you identify a female karyotype?

Presence of two X chromosomes Signup and view all the answers

What is the significance of unique chromosomal arrangements in offspring?

They contribute to genetic diversity Signup and view all the answers

What is the function of the replicated chromosome during cell division?

To ensure identical copies are passed on Signup and view all the answers

What is the primary purpose of meiosis?

To produce gametes with half the number of chromosomes Signup and view all the answers

In males, what is the outcome of meiosis?

Produces 4 viable sperm cells Signup and view all the answers

What occurs if nondisjunction happens during meiosis?

Gametes contain an abnormal number of chromosomes Signup and view all the answers

What is one characteristic of gametes produced through meiosis?

They are genetically distinct from the parent cell Signup and view all the answers

How many daughter cells are produced at the end of meiosis?

4 daughter cells with half the number of chromosomes Signup and view all the answers

Which of the following best describes Down syndrome?

A condition caused by an extra copy of chromosome 21 Signup and view all the answers

In females, what is the result of the unequal division of cytoplasm during meiosis?

Formation of 1 viable egg and 3 polar bodies Signup and view all the answers

What is a common genetic outcome of errors during meiosis?

Chromosomal disorders due to abnormal gametes Signup and view all the answers

What is the primary cause of sterility in Turner syndrome?

Underdeveloped internal organs Signup and view all the answers

What characterizes Klinefelter syndrome?

Small testes and potential secondary female characteristics Signup and view all the answers

What is the basic unit of heredity?

Gene Signup and view all the answers

How many unique chromosomes do human somatic cells typically have?

23 Signup and view all the answers

What is the relationship between homologous chromosomes?

They share the same genes but may have variations. Signup and view all the answers

What determines whether a recessive allele is expressed in an individual?

Having two copies of the allele Signup and view all the answers

What does the term 'genotype' refer to?

The combination of alleles for a specific gene Signup and view all the answers

Which of the following statements is true regarding dominant alleles?

They always express a trait when present. Signup and view all the answers

Study Notes

Lecture 12: Cell Division & Intro to Genetics

Today's Lecture Topics:
- Terminology review
- Importance of cell division
- Human life cycle
- Mitosis
- Meiosis
- Chromosomal disorders
- Introduction to genetics
Reading Material: Chapter 19
Chromosomes: Individual DNA molecules housed within the nucleus of cells.
Genes: Specific regions on chromosomes that contain instructions for all traits.
Tissue Cells: Contain 46 chromosomes (two sets of 23, one from each parent).
Gametes (sperm/egg): Contain 23 unique chromosomes.
Karyotype: A visual representation of an individual's chromosomes, arranged from largest to smallest. Karyotypes are used to identify chromosomal abnormalities. This specific sample is a tissue cell, not a gamete.
Autosomal Chromosomes: 22 pairs of chromosomes that do not determine sex.
Sex Chromosomes: One pair of chromosomes that determine sex (XX for female, XY for male). A tissue cell from a male has one X and one Y chromosome.
Homologous Chromosomes: Pairs of chromosomes that share the same genes (one from each parent). Each of these pairs are the same and share the same genes.
Cell Division Importance: Crucial for reproduction, growth, development and tissue repair.
Mitosis:
- Produces two identical daughter cells.
- DNA replication occurs before mitosis.
- Chromosomes are duplicated, aligned and separated.
- Necessary for growth, development, and repair of tissues.
- Examples of cells undergoing mitosis include skin cells.
Meiosis:
- Produces four daughter cells (gametes). Each gamete contains one set of chromosomes (haploid).
- Essential for sexual reproduction.
- Enables genetic variation among offspring. The process halves the number of chromosomes in the gametes.
Conception: Fusion of one sperm (23 chromosomes) and one egg (23 chromosomes) to form a zygote (46 chromosomes).
Zygote Development: The single-celled zygote grows by repeated cell division.
Chromosome Replication: Each chromosome must make an identical copy before cell division. The identical duplicates are attached at a midpoint and are called a replicated chromosome. The duplicated chromosomes are split and moved to opposite ends of the cell.
Nondisjunction: Errors during meiosis that can result in gametes with an abnormal number of chromosomes. This can result in chromosomal disorders.
Down Syndrome: Individuals with a third copy of chromosome 21. This is detected by having an extra chromosome 21 in a karyotype.
Turner Syndrome: Females with only one X chromosome.
Klinefelter Syndrome: Males with extra X chromosomes (XXY).
Genetics/Heredity: The study of inherited traits. Traits are determined by genes on chromosomes.
Genes: Basic units of heredity located on chromosomes. Each gene is a section of chromosome that carries instructions to build specific proteins.
Alleles: Different variations of a gene.
Dominant Allele: Always expressed as a trait.
Recessive Allele: Only expressed when two copies are present.
Genotype: The combination of alleles an individual has for a particular gene.
Homozygous: An individual with two identical alleles for a gene (e.g., EE or ee).
Heterozygous: An individual with two different alleles for a gene (e.g., Ee).
Phenotype: The visible or measurable expression of a trait.
Examples of different traits: Freckles, widow's peak, attached earlobes and tongue rolling.

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This quiz covers the key concepts of cell division and the fundamentals of genetics as outlined in Chapter 19. Explore important topics such as mitosis, meiosis, chromosomal structures, and genetic terminology. Test your understanding of the human life cycle and the significance of chromosomal disorders.