Lecture 12 Flashcards by Alysa Freeman

What is Sexual Reproduction?

The way more complex organisms reproduce, leading to genetically unique offspring

It involves combining genetic material from two parents.

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How do bacterial cells reproduce?

Asexually, producing identical daughter cells

Each daughter cell has the same set of genes as the mother cell.

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What is the chromosome count in human body cells before division?

46 chromosomes

These chromosomes are replicated before cell division.

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What results from Mitosis and Cytokinesis?

Each daughter cell receives the same 46 chromosomes as the mother cell

This process maintains genetic consistency in asexual reproduction.

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Why are sexually reproducing organisms genetically unique?

They inherit a combination of genes from two genetically different parents

This leads to genetic diversity among offspring.

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What is the significance of sexual reproduction in evolution?

It speeds up the selection process for survival of the fittest

Organisms with beneficial gene combinations are more likely to survive.

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What is Asexual Reproduction?

Occurs in primitive organisms, producing genetically identical offspring

Involves only Mitosis.

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What is Sexual Reproduction characterized by?

Involves an exchange of genetic material, producing genetically unique offspring

This process combines chromosomes from two parents.

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What are Diploid Cells?

Cells that have two sets of chromosomes, totaling 46 in humans

All somatic cells in humans are diploid.

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What are Haploid Cells?

Cells that contain only one set of chromosomes, totaling 23 in humans

These are also known as sex cells or gametes.

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What is the function of Gonads?

To produce gametes for sexual reproduction

Testes produce sperm, and ovaries produce eggs.

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What is Gametogenesis?

The process of producing haploid sex cells in gonads

It includes meiosis and subsequent maturation.

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What is Meiosis?

A specialized type of cell division that reduces chromosome number by half

It consists of two divisions: Meiosis I and Meiosis II.

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What is the outcome of Meiosis?

4 haploid cells, each with 23 chromosomes

These cells are gametes ready for fertilization.

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What is a Zygote?

The first diploid cell formed after fertilization

It contains 46 chromosomes, combining genetic material from both parents.

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What is Embryogenesis?

The complex process of an embryo developing into a variety of tissues and organs

It involves cell division, differentiation, and sometimes cell death.

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What are Homologous Chromosomes?

Chromosome pairs that contain genes coding for the same traits

Each pair consists of one chromosome from each parent.

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What is crossing-over?

The exchange of genetic material between homologous chromosomes during meiosis

This process increases genetic diversity.

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What is the chromosome count in a human zygote?

46 chromosomes

This is the result of 23 chromosomes from each parent.

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Fill in the blank: The process of combining 2 haploid cells from different organisms is known as _______.

Fertilization

It results in the formation of a zygote.

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Fill in the blank: A fertilized egg is called a _______.

Zygote

It is the first diploid cell in development.

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True or False: All cells in the human body are diploid.

False

Only somatic cells are diploid; gametes are haploid.

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What is the process of homologous chromosomes getting separated during meiosis called?

Segregation

This process occurs during Meiosis I.

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What is the failure of homologous chromosomes to separate during Meiosis I called?

Nondisjunction

This results in abnormal gametes.

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During which phase of meiosis do homologous chromosomes separate?

Meiosis I ## Footnote This is a critical step in the meiotic process.

Homologous chromosomes are defined as:

The chromosomes that come from two different parents, but contain gene coding for the same traits ## Footnote This includes pairs that carry the same genes but may have different alleles.

True or False: Down syndrome is the result of an abnormal number of chromosomes.

True | An extra copy of chromosome #21 ## Footnote Specifically, Down syndrome is caused by Trisomy 21.

What chromosomal pair is referred to as the sex chromosomes?

Pair #23 ## Footnote This pair determines the sex of the offspring. XX (female), XY (male)

What is the default setting for embryonal development?

Femaleness ## Footnote All embryos initially develop as females unless a Y chromosome is present.

What is the role of the Y chromosome?

Codes exclusively for maleness ## Footnote It triggers the development of male characteristics. The “Y” chromosome codes only for maleness because it codes for Testosterone. There are no other vital genes coded on this chromosome.

X-linked genetic disorders are caused by:

Mutant genes found on X chromosome #23 ## Footnote These disorders can manifest differently in males and females. EX: red-green color blindness, Becker’s muscular dystrophy, Hemophilia

If a female has one mutant gene on one of her X chromosomes, she will:

Not express the genetic disorder, but will be a carrier of the bad gene ## Footnote Females have a backup copy of the X chromosome.

Sperm cells are produced in:

Seminiferous tubules ## Footnote This is where spermatogenesis occurs.

Where are the testes located?

In the scrotum ## Footnote This location is necessary for optimal sperm production temperature.

What is the correct order for sperm traveling through the male reproductive tract?

Seminiferous tubules, Epididymis, Vas Deferens, Urethra ## Footnote This path is critical for sperm maturation and ejaculation.

Which gland produces fructose to fuel spermatozoa?

Seminal Vesicle ## Footnote It also produces antibacterial enzymes.

What is the function of the prostate gland in the male reproductive system?

To make a base to neutralize the acidity of the female reproductive tract ## Footnote This helps ensure the survival of sperm cells.

The uterus is made of three layers of tissue. Name them.

* Endometrium * Myometrium * Perimetrium ## Footnote These layers play different roles in the reproductive process.

Where does fertilization most likely occur?

In the fallopian tube

What is the inner lining of the uterus called?

Endometrium

What is the layer of smooth muscle in the uterine wall?

Myometrium

What is the outer layer of the uterus made of?

Serosa

What is the top of the uterus referred to as?

Uterine Fundus

What is the body of the uterus called?

Antrum

What does the uterine cervix lead to?

Vaginal Canal

What begins to form at the site of embryonal implantation?

Placenta

What is the process called when the endometrium is shed?

Menstrual flow

True or False: Fetal and maternal blood mix.

False

If no fertilization occurs, how long does the egg survive in the fallopian tube?

About 1 day

Fill in the blank: The placenta allows nutrients and metabolites to pass from _______ circulation into fetal blood.

Maternal

Gonads are

the Testes in males and the Ovaries in females

Testes produce gametes called

Spermatozoa, or sperm cells

Ovaries produce gametes called

Ova or Oocytes, or egg cells

Steps of Gametogenesis:

1. Reduction of the number of chromosomes from 46 to 23 (from diploid to haploid): involves a special kind of cell division called Meisosis. 2. Differentiation and maturation of the haploid cell into a functional gamete. After meiosis and the creation of cells with only one set of chromosomes, these cells must be matured. For males, this step occurs when a haploid cell in a male testis becomes a sperm cell. For females, a haploid cell in a female ovary becomes an egg cell. ## Footnote Then they will be able to combine their DNA sets to produce an offspring.

Steps of Meiosis

1. a diploid cell with 46 unreplicated chromosomes 2. a diploid cell with 46 replicated chromosomes (X’s) 3. after Meiosis I: 2 cells with 23 replicated chromosomes (X’s) in each 4. after Meiosis II: 4 cells with 23 unreplicated chromosomes in each

____ is the process of combining 2 haploid cells from 2 different organisms, resulting in a new diploid cell.

Fertilization

Human offspring for the first 8 weeks of gestation is referred to as an ____ because it is in the process of forming new organs

Embryo

Once all the organs are in place, the Embryo becomes a ____, which keeps developing and growing the organs that are already in place.

Fetus

Which of the following is NOT true about an embryo and a fetus? a. Embryo is what a fertilized egg becomes, as it develops over 2 months b. The embryo develops new organs c. Once all the organs are formed, the embryo is called a fetus d. Fetus continues forming new organs until birth e. Offspring in womb from 8 weeks until 40 weeks of gestation is referred to as a fetus

d. Fetus continues forming new organs until birth

Which of the following is NOT true about a zygote? a. It has 46 chromosomes b. It is considered a diploid cell c. It begins dividing and multiplying many times d. It develops into an embryo. e. It has 1 set of chromosomes

e. It has 1 set of chromosomes

Steps that occur with successful Meiosis

1. Alignment of homologous chromosomes and crossing-over; i.e. exchange of genetic information 2. Segregation of homologous chromosomes (happens independently in each pair) 3. Formation of 2 nuclei 4. Replication of centromeres and the splitting of X-s in half 5. Formation of 4 haploid cells with 23 unreplicated single chromosomes in each

Only 1 chromosome instead of 2 in the zygote (offspring)

Monosomy

3 chromosomes instead of 2 in the zygote (offspring)

Trisonomy

The first 22 chromosomal pairs are always homologous and called

Autosomes

The Testes are kept in a little bag of skin called the

Scrotum

The production of sperm cells takes place in tiny little tubes called ____, from where the newly made spermatozoa are drained into ____.

Seminiferous Tubules Epididymis

The Testis is connected to the accessory reproductive organ inside the pelvic cavity by a tube called the ____.

Vas Deferens

Function of Bulbourethral gland a.k.a. Cowper's gland:

adds lubricating mucus

The Spermatozoa, with the secretions of these three glands, then exit the body via the ____ as a mixture called Semen.

Urethra

Sperm production

1. Sperm cells are produced in Seminiferous Tubules 2. They are collected in the Epididymis 3. They exit the Testis via Vas Deferens 4. They pick up secretions from the Seminal Vesicle, Prostate Gland, and Cowper's gland 5. The mixture of secretions and sperm cells exit via the urethra

When exiting the testes, the sperm goes through the male reproductive tract in this order:

Seminiferous tubules, Epididymis, Vas Deferens, Urethra

The female Sex cells (or Gametes) are produced in the

Ovaries

The outer layer of the uterus made of serosa

Perimetrium

The uterus narrows to form the

Uterine Cervix (or neck)