Genetics Flashcards
Define biotechnology
Any technological application that uses biological systems, living organisms or processes to make or modify products or processes for specific use
Define characteristic
Feature defined by a standard of points or identified features. Eg hair colour, height, age. Some are inherited, some are not.
Define chromosome
A thread-like structure found in the nucleus of all cells (except red blood cells), where DNA is packaged up in sections to protect it.
Define DNA
Deoxyribonucleic acid; a molecule that contains the biological instructions that make each species unique
Define gene
A short section of DNA that carry instructions for discrete functions or products
Define mutation
A change in the DNA sequence of an organism
Define replication
The process of making an identical copy of something.
Define reproduction
The biological process by which new individual organisms are produced from their “parents”
Both gender’s gametes and its characteristics
Sperm:The human sperm cell is the reproductive cell in males. Sperm cells determine the sex of a child.
Ova (singular ovum): The egg cell is the largest human cell. It is just visible to the naked eye. The egg cell is also the roundest cell.
Name of organs that produces gametes
Testes and Ovaries
Gonads for both
Define gestation
The process or period of developing inside the womb between conception and birth.
To maximise the chance of fertilisation occurring, millions of sperm must be:
produced and stored at a favourable temperature,
able to travel a long distance and
able to survive in the hostile environment of the female reproductive tract.
How is the sperm kept alive?
Semen, the fluid in which sperm swim, contains substances produced by various glands to help them survive their gruelling journey to reach the egg
What is the female reproductive system designed to do?
produce female gametes (ova, or eggs)
provide a suitable environment in which ova can be fertilised by sperm (male gametes)
nourish and protect the fertilised ovum through pregnancy
give birth to the baby when its development is complete
produce female hormones which:
- control the female reproductive cycle, and
- cause the development of female characteristics (e.g. breasts, which nourish the baby after birth).
Define allele
Each of two or more alternative forms of a gene that arise by mutation and are found on a chromosome.
How is a new organism formed during sexual reproduction?
Sexual reproduction begins when male and female sex cells (known as gametes) fuse to form a new cell called a zygote. The zygote contains a mix of traits inherited by its parents. The zygote cell then divides over and over again to form a new organism. Each gamete only carries half the information needed to make an organism, therefore fertilisation is required to form a zygote.
Vas deferens structure & function
Two tubes, each connecting a testicle with the urethra
The vas deferens transports mature sperm to the urethra in preparation for ejaculation.
Seminal vesicle structure & function
A pair of glands in males that are positioned below the urinary bladder
Glands that produce the fluids that will turn into semen.
Epididymis structure & function
Coiled tubes at the top of the testes
It carries and stores sperm cells that are created in the testes. It’s also the job of the epididymis to bring the sperm to maturity — the sperm that emerge from the testes are immature and incapable of fertilization.
Testes structure &function (single is called testicle)
Two endocrine glands found in the scrotum made up of tightly, tiny coiled tubes (seminiferous tubules)
The testes are responsible for making sperm and are also involved in producing a hormone called testosterone.
Urethra structure & function
A hollow tube positioned between the urinary bladder and urinary meatus which takes urine stored in the bladder out of the body.
The urethra is the tube that carries urine from the bladder to outside of the body. In males, it has the additional function of ejaculating semen when the man reaches orgasm. When the penis is erect during sex, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm
Scrotum structure & function
It has the shape of a sac and divides into two compartments.
It holds the testes in place. The scrotum acts as a “climate control system” for the testes. For normal sperm development, the testes must be at a temperature slightly cooler than body temperature
Penis structure & function
Organ of spongy, erectile tissue, becomes engorged with blood when a man is sexually aroused.
The function of the penis, in addition to aiding in urination, is to assist with reproduction by transporting sperm to the female reproductive system. During sexual intercourse, the penis becomes erect and stiffens, allowing a person to insert it into an orifice, such as the vagina
Ovary structure & function
Two endocrine glands containing immature ova
produce and release: female hormones (oestrogen and progesterone) mature ova (usually once per menstrual cycle)
How does the female reproductive system work?
The ovaries produce the egg cells, called the ova or oocytes. The oocytes are then transported to the fallopian tube where fertilization by a sperm may occur. The fertilized egg then moves to the uterus, where the uterine lining has thickened in response to the normal hormones of the reproductive cycle. Once in the uterus, the fertilized egg can implant into thickened uterine lining and continue to develop. If implantation does not take place, the uterine lining is shed as menstrual flow. This cycle is maintained through the production of female sex hormones.
How does the male reproductive system work?
The release process starts when the penis fills with blood and becomes erect. Continuing to stimulate the penis will cause an ejaculation. Mature sperm begin their journey by travelling from the epididymis to the vas deferens, which propels sperm forward with smooth muscle contractions. The sperm arrive first at the ampulla just above the prostate gland. Here secretions from the seminal vesicle located next to the ampulla are added.
Next the seminal fluid is propelled forward through the ejaculatory ducts toward the urethra. As it passes the prostate gland, a milky fluid is added to make semen.
Finally, the semen is ejaculated from the penis through the urethra.
Uterus structure & function
Hollow organ with thick muscular wall
It functions to nourish and house a fertilized egg until the fetus, or offspring, is ready to be delivered.
Cervix structure & function
Narrow opening between uterus and vagina (strictly speaking, not actually an organ)
It allows sperm passage into the uterus through the endocervical canal and it must produce mucus to facilitate sperm entry.
Fallopian tube structure & function
Two muscular tubes, each connecting an ovary with the uterus inner surfaces lined with cilia (hair-like cells)
It transports the ova from the ovary to the uterus each month. In the presence of sperm and fertilization, the uterine tubes transport the fertilized egg to the uterus for implantation.
Vagina structure & function
Elastic, muscular tube connecting uterus with the outside of the body
It’s where the penis is inserted during sexual intercourse. It’s the pathway (the birth canal) through which a baby leaves a woman’s body during childbirth.
Define gonads
An organ that produces gametes
Sex of sperm cells
X chromosome= female
Y chromosome=male
Describe the fertilisation process
1) The sperm move towards the egg by muscular contractions (in ‘waves’) that move along the uterus. The sperm also swim using their tails. Many of the sperm arrive at the egg at the same time, however only one will penetrate the egg wall to fertilize the egg.
2) The fertilized egg travels down the oviduct to the womb. By the time it reaches the womb, the egg is a ball of cells ready to attach itself to the surface of the womb. From this point a placenta begins to grow.
3) The zygote buries itself into the wall of the uterus and it absorbs nourishment from here. This is called implantation. A hormone is released at this stage that stops the woman from menstruating and she is now said to be pregnant.
