Questions and Answers
What does a karyotype show?
What is a genome?
The full set of genetic information that an organism carries in its DNA.
When do scientists photograph chromosomes to see them clearly?
During mitosis.
Why do our chromosomes come in pairs?
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How many sex chromosomes are there in the human genome?
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What does XX represent?
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What does XY represent?
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Why are males and females at a 50:50 ratio?
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Which chromosome is bigger, X or Y?
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What are autosomal chromosomes?
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What patterns of inheritance do human traits follow?
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What does MCIR determine?
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Give an example of simple dominance.
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Give an example of co-dominance.
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What are the genotypes for blood type AB?
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What are the possible genotypes for blood type A?
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What are the possible genotypes for blood type B?
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What is the genotype for blood type O?
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What is a sex-linked gene?
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Why does colorblindness occur more in males than females?
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How do female cells adjust to an extra X chromosome?
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How can you be certain that a cat with three colors is female?
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How can pedigrees be used to analyze human inheritance?
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What is a pedigree?
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Pedigrees can only be used for humans.
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What does a circle represent on a pedigree chart?
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What does a square represent on a pedigree chart?
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What does a horizontal line represent on a pedigree chart?
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What does a shaded shape mean on a pedigree chart?
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What does a vertical line represent on a pedigree chart?
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What does a non-shaded shape represent on a pedigree chart?
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Study Notes
Karyotype
- Represents the complete diploid set of chromosomes arranged by size.
- Chromosomes are displayed in pairs, helping identify structural abnormalities.
Genome
- Refers to the entire set of genetic information encoded in an organism’s DNA.
Chromosome Photography
- Chromosomes are photographed during mitosis for clear visualization as they are fully condensed at this stage.
Chromosome Pairs
- Humans possess paired chromosomes (46 total) due to the union of haploid cells (sperm and egg; each contributing 23 chromosomes).
Sex Chromosomes
- Among the 46 human chromosomes, 2 are sex chromosomes, determining an individual's sex.
Gender Indicators
- XX denotes a female.
- XY denotes a male.
Gender Ratio
- The sex ratio of 50:50 arises because eggs carry only X chromosomes, while sperm can carry either X or Y.
Size of Sex Chromosomes
- The X chromosome contains over 1200 genes while the Y chromosome contains around 140 genes, making X significantly larger.
Autosomal Chromosomes
- The remaining 44 chromosomes in humans that are not classified as sex chromosomes.
Patterns of Inheritance
- Human traits exhibit patterns of simple dominance, codominance, and sex-linkage.
MCIR Gene
- The MCIR gene plays a crucial role in the determination of skin and hair color.
Simple Dominance Examples
- Traits influenced by simple dominance include those determined by the MCIR and RH genes.
Codominance Example
- The ABO blood group exemplifies codominance, where both IA and IB alleles are expressed.
Blood Type Classifications
- Blood type AB results from the presence of both IA and IB alleles.
- Blood type A can be IA/IA or IA/i.
- Blood type B can be IB/IB or IB/i.
- Blood type O is characterized by ii genotype.
Sex-Linked Genes
- These are genes located on the sex chromosomes, often influencing traits related to gender.
Colorblindness
- More prevalent in males because it requires only one affected X chromosome, while females need two.
X Chromosome Adjustment in Females
- In females, one X chromosome is randomly inactivated, creating a Barr body, a dense region that typically does not result in expression of most genes.
Color Variance in Female Cats
- Female cats can exhibit tortoiseshell coloring due to the random inactivation of X chromosomes, allowing for the expression of both black and orange fur.
Pedigree Analysis
- Pedigrees provide insight into the inheritance patterns of specific traits through family charts.
Pedigree Chart Components
- A pedigree chart visually outlines familial relationships, aiding in the tracking of inherited traits.
- Circles represent females, while squares represent males.
- Horizontal lines indicate marriage, and vertical lines connect parents to their offspring.
- Shaded shapes indicate individuals possessing a trait, while non-shaded shapes indicate those who do not.
Pedigrees in Other Species
- Pedigrees are not limited to human analysis; they can be used for studying inheritance in various species.
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Description
Test your knowledge of key concepts from Biology Chapter 14 with these flashcards. This chapter focuses on important genetic terms and processes, such as karyotypes and genomes. Enhance your understanding of chromosomes and their roles in heredity.
