Biology Chapter 14 Flashcards

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Questions and Answers

What does a karyotype show?

Only autosomal chromosomes

The complete haploid set of chromosomes

Only sex chromosomes

The complete diploid set of chromosomes grouped in pairs (correct)

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?

A diploid cell develops from a haploid sperm and egg, resulting in 46 chromosomes. Signup and view all the answers

How many sex chromosomes are there in the human genome?

2 Signup and view all the answers

What does XX represent?

Female Signup and view all the answers

What does XY represent?

Male Signup and view all the answers

Why are males and females at a 50:50 ratio?

An egg carries an X chromosome, while a sperm can carry either X or Y. Signup and view all the answers

Which chromosome is bigger, X or Y?

X Signup and view all the answers

What are autosomal chromosomes?

The other 44 chromosomes that are not sex chromosomes. Signup and view all the answers

What patterns of inheritance do human traits follow?

Simple dominance, co-dominance, and sex-linkage. Signup and view all the answers

What does MCIR determine?

Skin and hair color. Signup and view all the answers

Give an example of simple dominance.

MCIR and RH. Signup and view all the answers

Give an example of co-dominance.

ABO blood group. Signup and view all the answers

What are the genotypes for blood type AB?

IA and IB. Signup and view all the answers

What are the possible genotypes for blood type A?

IA and IA or IA and i. Signup and view all the answers

What are the possible genotypes for blood type B?

IB and IB or IB and i. Signup and view all the answers

What is the genotype for blood type O?

ii. Signup and view all the answers

What is a sex-linked gene?

A gene located on a sex chromosome. Signup and view all the answers

Why does colorblindness occur more in males than females?

Males require only one affected X chromosome, whereas females require two. Signup and view all the answers

How do female cells adjust to an extra X chromosome?

Most genes in one X chromosome are randomly turned off, forming a Barr body. Signup and view all the answers

How can you be certain that a cat with three colors is female?

A female cat has two X chromosomes, resulting in a mix of colors. Signup and view all the answers

How can pedigrees be used to analyze human inheritance?

They help determine the nature of genes and alleles associated with traits. Signup and view all the answers

What is a pedigree?

A chart that shows relationships within a family. Signup and view all the answers

Pedigrees can only be used for humans.

False Signup and view all the answers

What does a circle represent on a pedigree chart?

Female. Signup and view all the answers

What does a square represent on a pedigree chart?

Male. Signup and view all the answers

What does a horizontal line represent on a pedigree chart?

Marriage. Signup and view all the answers

What does a shaded shape mean on a pedigree chart?

Possesses trait. Signup and view all the answers

What does a vertical line represent on a pedigree chart?

Parents with offspring. Signup and view all the answers

What does a non-shaded shape represent on a pedigree chart?

Doesn't possess trait. Signup and view all the answers

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.