You-Nique revision

Question 1

Identify the sex chromosomes in males and females.

Answer 1

• Males have XY chromosomes.
• Females have XX chromosomes.

Question 2

Whats the number of chromosomes present in a normal humans cells and gametes (egg and sperm cells)?

Answer 2

• Normal human cells have 46 chromosomes
• Egg and sperm cells (gametes) have 23 chromosomes

Question 3

What is a karyotype?

Answer 3

A karyotype is a picture of chromosomes used to check for genetic conditions.

Question 4

How is a karyotype used?

Answer 4

Identify Chromosome Abnormalities: It helps detect extra or missing chromosomes (e.g., Down syndrome).

Determine Sex: It shows whether someone has XX (female) or XY (male) chromosomes.

Study Genetic Disorders: It helps diagnose conditions linked to chromosome changes, like Turner syndrome or Klinefelter syndrome.

Examine Chromosome Structure: It can show structural changes like deletions, duplications, or translocations.

Question 5

Describe the amount of chromosomes found in normal human cells and gametes (egg and sperm cells) using haploid and diploid.

Answer 5

• normal human cells (46 chromosomes) are diploid
• gametes (egg and sperm cells) (23 chromosomes) are haploid

Question 6

What are homologous chromosomes?

Answer 6

Homologous chromosomes are pairs of chromosomes, one from each parent, that are similar in shape, size, and genetic content.

Question 7

Define autosomes.

Answer 7

• autosomes are the non-sex chromosomes
• there are 44 autosomes in a human (22 pairs)

Question 8

Define sex chromosomes.

Answer 8

• Sex chromosomes determine an individual’s sex.
• In humans, females have XX chromosomes, and males have XY chromosomes.

Question 9

Explain the relationship between genes, chromosomes and DNA.

Answer 9

• DNA carries genetic information
• Genes are parts of DNA
• chromosomes are structures that hold genes.

Question 10

Name the 4 nitrogenous bases in DNA.

Answer 10

• Adenine (A)
• Thymine (T)
• Cytosine (C)
• Guanine (G)

Question 11

What are the complementary base-pairing rules with the 4 nitrogenous bases?

Answer 11

• Adenine pairs with Thymine (A-T)
• Cytosine pairs with Guanine (C-G)

Question 12

What unique features do homologous chromosomes share?

Answer 12

Homologous chromosomes share the same genes at the same locations, but may have different versions (alleles) of those genes.

Question 13

How can you distinguish between a male and female karyotype?

Answer 13

A male karyotype has one X and one Y chromosome (XY), while a female karyotype has two X chromosomes (XX).

Question 14

How can you recognize Down syndrome in a karyotype?

Answer 14

Down syndrome is characterized by an extra copy of chromosome 21 (trisomy 21).

Question 15

How can you recognize Klinefelter’s syndrome in a karyotype?

Answer 15

Klinefelter’s syndrome is characterized by an extra X chromosome in males (XXY).

Question 16

How can you recognize Turner’s syndrome in a karyotype?

Answer 16

Turner’s syndrome is characterized by a missing X chromosome in females (X0).

Question 17

What are some examples of inherited traits?

Answer 17

Examples of inherited traits include eye color, hair color, and blood type.

Question 18

What is the difference between dominant and recessive traits?

Answer 18

Dominant traits are expressed if at least one dominant allele is present (e.g., “A”), while recessive traits are only expressed if both alleles are recessive (e.g., “a”).

Question 19

What lettering symbols are used for dominant and recessive traits?

Answer 19

Dominant traits are represented by uppercase letters (e.g., “A”), and recessive traits are represented by lowercase letters (e.g., “a”).

Question 20

What factors can influence phenotype?

Answer 20

Phenotype is influenced by genetics (genotype), environment (e.g., diet, climate), and interactions between genes and the environment.

Question 22

What is an allele?

Answer 22

An allele is a version of a gene that can exist in different forms (e.g., dominant or recessive).

Question 23

What does homozygous mean?

Answer 23

Homozygous means having two identical alleles for a particular gene (e.g., AA or aa).

Question 24

What does heterozygous mean?

Answer 24

Heterozygous means having two different alleles for a particular gene (e.g., Aa).

Question 25

What are phenotypes of offspring?

Answer 25

Phenotypes of offspring are the observable traits, such as eye color or height, determined by the combination of alleles they inherit.

Question 26

Punnett square:

Answer 26

A a +-----+-----+ A | AA | Aa | +-----+-----+ a | Aa | aa | +-----+-----+

Question 27

What is a Punnett square used for?

Answer 27

A Punnett square is used to predict the possible genotypes and phenotypes of offspring based on the parents' genotypes.

Question 28

How do you interpret a Punnett square?

Answer 28

After filling in the Punnett square, the combinations show the possible genotypes, and you can predict the phenotypes by considering dominant and recessive traits.

Question 29

What is a pedigree chart used for?

Answer 29

A pedigree chart is used to show the inheritance patterns of traits through generations in a family.

Question 30

How do you interpret a pedigree chart?

Answer 30

In a pedigree chart: Squares represent males, and circles represent females. A filled square or circle shows that the individual expresses the trait (affected). A half-filled square or circle shows that the individual is a carrier (heterozygous). A blank square or circle shows that the individual does not express the trait.

Question 31

Instructions on a pedigree chart

Answer 31

To draw a pedigree chart: Start with the oldest generation at the top, and use squares for males and circles for females. Connect parents with a horizontal line and children with vertical lines. Fill in the symbols based on the information provided (affected, unaffected, carrier, etc.). Continue adding generations downward in chronological order.