Biology Chapter: DNA and Cell Division

DNA is a double-stranded molecule located in the nucleus that contains the genetic information necessary for producing proteins.

Haploid cells contain one complete set of chromosomes (23 in humans), while diploid cells contain two sets (46 in humans).

Chromosomes are structures made of DNA and protein that organize genetic material, with humans having 46 chromosomes divided into 23 pairs.

<p>Genes are short sections of DNA that code for proteins, giving organisms their specific traits inherited from their parents.</p> Signup and view all the answers

<p>Cell division is crucial for growth, repair, and maintenance of tissues in multicellular organisms.</p> Signup and view all the answers

<p>Improved nutritional content and drought tolerance.</p> Signup and view all the answers

<p>The nucleus was taken from a mammary gland cell and placed into an empty egg cell, which was then stimulated to divide.</p> Signup and view all the answers

<p>Adult somatic cells are highly differentiated and require epigenetic reprogramming to revert to a pluripotent state.</p> Signup and view all the answers

<p>The embryo is transferred into a surrogate mother.</p> Signup and view all the answers

<p>Differentiation is the process by which unspecialized stem cells become specialized in structure and function.</p> Signup and view all the answers

<p>The potential for embryos to be experimented on raises ethical concerns regarding their status as potential lives.</p> Signup and view all the answers

<p>Biotechnology can create drought-tolerant crops, ensuring food supplies in water-scarce areas.</p> Signup and view all the answers

<p>Epigenetic modifications in somatic cells can hinder the reprogramming necessary for successful cloning.</p> Signup and view all the answers

<p>Sister chromatids are identical copies of a chromosome joined at the centromere, while homologous chromosomes are paired chromosomes from each parent with potentially different alleles.</p> Signup and view all the answers

<p>A tetrad is a foursome of chromatids that forms when replicated homologous chromosomes align during meiosis I.</p> Signup and view all the answers

<p>Crossing over is the exchange of DNA between paired homologous chromosomes during meiosis, increasing genetic diversity by creating new allele combinations.</p> Signup and view all the answers

<p>Spindle fibers help move and separate chromosomes during both mitosis and meiosis, ensuring proper distribution of genetic material to daughter cells.</p> Signup and view all the answers

<p>Spermatogenesis produces four functional sperm per cycle and continues throughout a male's life, while oogenesis typically produces one functional egg per cycle and is cyclic, occurring monthly.</p> Signup and view all the answers

<p>Menopause is defined as the cessation of menstrual cycles for at least 12 consecutive months and typically occurs between ages 45 and 55.</p> Signup and view all the answers

<p>Autosomes are non-sex chromosomes that carry the majority of an organism's genetic information, unlike sex chromosomes which determine an organism's sex.</p> Signup and view all the answers

<p>Segregation in meiosis is the separation of homologous chromosomes and their alleles into different gametes, ensuring genetic diversity among offspring.</p> Signup and view all the answers

<p>Alleles are different versions of a gene that determine specific traits. Each organism inherits two alleles for each gene, one from each parent.</p> Signup and view all the answers

<p>Mendel's Law of Segregation states that during gamete formation, the two alleles for a gene separate so that each gamete receives only one allele from each gene pair.</p> Signup and view all the answers

<p>Homozygous refers to an organism that has two identical alleles for a particular gene, such as AA or aa.</p> Signup and view all the answers

<p>Genotype is the genetic makeup of an organism, representing the alleles it carries, while phenotype is the observable physical expression of a trait that results from the genotype.</p> Signup and view all the answers

<p>A Punnett square is a tool used to predict the genetic outcomes and probabilities of different genotypes and phenotypes in offspring.</p> Signup and view all the answers

<p>In a pedigree, shaded shapes indicate individuals who express a particular trait or condition, while unshaded shapes represent individuals who do not express the trait.</p> Signup and view all the answers

<p>Mendel's Law of Independent Assortment states that different genes independently separate from one another when reproductive cells develop.</p> Signup and view all the answers

<p>'F1' stands for the first filial generation, which refers to the first generation of offspring resulting from a cross between two parental organisms.</p> Signup and view all the answers

<p>Nondisjunction is the failure of homologous chromosomes to separate during meiosis, resulting in one daughter cell with an extra chromosome and another with one less chromosome.</p> Signup and view all the answers

<p>Aneuploidy is the condition of having an abnormal number of chromosomes. Examples include trisomy (e.g., Down syndrome with 47 chromosomes) and monosomy (e.g., Turner syndrome with 45 chromosomes).</p> Signup and view all the answers

<p>Increased maternal age is associated with a higher incidence of meiotic nondisjunction, leading to conditions such as Down syndrome.</p> Signup and view all the answers

<p>Turner syndrome is a condition resulting from the monosomy of sex chromosomes, specifically having one X chromosome (XO). Characteristics include short stature, thick necks, and underdeveloped sexual features.</p> Signup and view all the answers

<p>Klinefelter syndrome occurs in individuals with an extra X chromosome (XXY), leading to lower testosterone levels and a feminized appearance. Affected individuals may experience infertility and language problems.</p> Signup and view all the answers

<p>A karyotype is the complete set of chromosomes in an individual, used to determine if there is a normal set of 46 chromosomes or identify chromosomal abnormalities.</p> Signup and view all the answers

<p>Polyploidy involves having more than two complete sets of chromosomes, while nondisjunction leads to an abnormal number of individual chromosomes. It is common in plants such as wheat and bananas.</p> Signup and view all the answers

<p>Nondisjunction during mitosis usually has minimal effect, affecting only one cell, while in meiosis, it can lead to significant genetic disorders in gametes that may result in multi-celled organisms.</p> Signup and view all the answers

<p>The Barr body represents the inactivated X chromosome, helping to balance gene expression between males and females by preventing excess gene activity from X-linked genes.</p> Signup and view all the answers

<p>Fruit flies are favored for genetic studies due to their short life cycle, large number of offspring, simple genetic makeup, observable traits, and low cost.</p> Signup and view all the answers

<p>In artificial insemination, sperm is placed in the female's reproductive tract without sexual intercourse, whereas in vitro fertilization involves fertilizing egg cells outside the body and then transferring the embryo to the uterus.</p> Signup and view all the answers

<p>Recombinant DNA is created by combining genetic material from different sources; for example, BT corn contains a gene from a soil bacterium that makes it resistant to corn borers.</p> Signup and view all the answers

<p>Plant cloning is simpler because plants can regenerate from root or stem cuttings, while animal cloning is complex and often fails due to specialized cell types that cannot easily regenerate.</p> Signup and view all the answers

<p>Biotechnology in agriculture can increase crop yields and create pest and disease-resistant crops, which reduces the necessity for chemical pesticides.</p> Signup and view all the answers

<p>Gene therapy involves inserting genes into an individual's cells to treat genetic diseases, aiming to correct or replace malfunctioning genes.</p> Signup and view all the answers

<p>Animal cloning has a lower success rate because it often requires specialized cells to be reprogrammed, which can have permanently turned off genes, making the process complex.</p> Signup and view all the answers