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.
How tightly compressed is DNA?
This DNA is wound and woundand wound up to make it compress very small. About 2 metres of DNA fits into a cell nucleus a thousand times smaller than a full stop.
Number of chromosomes humans have
46 (23 pairs)
The four nucleotides in DNA
Adenine, guanine, thymine, cytosine
Nucleotide pairs
A with T
C with G
Why is the order of the letters so important?
The order of these letters is what tells each cell to do everything it does. In the same way that the order of letters in a sentence has meaning, the order of the bases means something to your cell. Each chromosome is a huge book containing many sentences (genes), each saying how to make some particular thing
Define base pairs?
Nucleotides that pair together to form the structure of DNA
Define nucleotide
A molecule consisting of a nitrogen-containing base
What is the backbone of DNA composed of?
Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups.
Role of genes
Genes carry the information that determines specific traits, the features or characteristics that are passed to you (inherited) from your parents.
What are traits caused by?
Most traits are caused by several genes, but some are caused by only 1.
What do genes produce?
DNA in a gene spells out specific instructions for making proteins in the cell.
Proteins are the building blocks for everything in your body.
Each gene makes only 1 protein, but they can combine to make very complicated structures.
Define daughter cell
A cell formed by the division or budding of another cell.
Causes of mutations
Copying or reading errors.
Radiation, such as ultraviolet, x-rays or gamma-rays.
Chemicals (mutagens) such as formalin, asbestos, Agent Orange.
Types of mutations
Point mutations: A genetic alteration caused by the substitution of a single nucleotide for another nucleotide.
Chromosomal mutations - alterations that affect whole chromosomes and whole genes rather than just individual nucleotides.
Mutation example
Also known as trisomy 21, this is when a person has three copies of chromosome 21, instead of 2.
It is the most common chromosomal mutation, at about 1 in 1000 births.
This causes a variety of symptoms, including distinctive facial features, developmental delays, mild to moderate intellectual disabilities, and increased chance of heart issues, leukemia and vision problems.
With medical assistance and education, expected lifespan is about 60 years (up from 9 years in 1910)
Biotechnology examples
Selective breeding (ie dog, cow, rose, horse etc)
Selecting and using living things to make stuff for us (eg bread / cake, beer / alcohol, cheese, etc)
Creating vaccines and medicines based on a detailed understanding of how disease organisms and our bodies work (HPV, personalised medicine, cancer vaccines, artificial organs, etc).
Using biological and genetic knowledge to obtain information (eg genetic fingerprinting / DNA testing, paternity tests, genetic counselling, etc)
Define bioethics
Bioethics: applying ethics to biology and biotechnology
Difference between haploid and diploid
gametes are haploid (one copy of each chromosome) n=23
Somatic cells are diploid (two copies of each chromosome) 2n=46.
Define meiosis
Meiosis is the process of cell division that produces haploid gametes.
Zygote characteristics
Diploid number of chromosomes
Half of chromosomes come from sperm and nucleus of egg cell
Human chromosome description
The body cells of an adult human contain 23 pairs (46 total) of chromosomes, 22 autosomes, numbered 1-22, and one sex chromosome, either an X chromosome or a Y chromosome.
The human male has 22 pairs of normal chromosomes (autosomes), one X chromosome, and one Y chromosome.
The human female has the normal 22 pairs and two X chromosomes.
Define mitosis
A type of cell division that takes place in body cells for :
growth
repair and maintenance
asexual reproduction
What are chromosomes composed of?
They are composed of a substance called chromatin ( a combination of DNA and protein)
Purpose of DNA and protein
The DNA within chromosomes carries the cell’s genetic information, while protein is mainly involved in the packaging of the DNA within the cell.
Number of chromosomes in each cell
The cells in the human body each contain 46 chromosomes arranged in 23 pairs and are referred to as diploid. The only exceptions are:
red blood cells,which have no nucleus.
gametes- the sperm and egg cells - which only contain 23 chromosomes (one of each pair) and are referred to as haploid.
Define chromatid
A chromatid is one half of a duplicated chromosome.
define the chromosomes in homologous pairs.
Two chromosomes that are identical, with the same genes.
Define paternal & maternal chromosomes
Chromosomes inherited from the father are called paternal chromosomes.
Chromosomes inherited from the mother are called
maternal chromosomes.
Who helped determine the structure of the DNA molecule?
James Watson, Francis Crick, Rosalind Franklin and Maurice Wilkins all played a pivotal role in determining the structure of the DNA molecule.
Who discovered the double helix shape?
Franklin’s work on X-ray diffraction showed that DNA had the characteristics of a helix.
Describe the external structure of DNA
The DNA molecule consists of two long, thin threads of complementary nucleotides that run antiparallel to each other and are held together by hydrogen bonds. The double helix shape of DNA is often compared to a twisted ladder.
A nucleotide consists of?
sugar phosphate group and a a nitrogenous base. In DNA there are four different types of nitrogen bases: adenine (A), guanine (G),cytosine (C) and thymine (T). Backbone consists of: Deoxyribose Sugar Phosphate
How are proteins created?
An organism’s DNA contains the instructions for making all the proteins that it needs to keep it functioning properly. The instructions are in the bases that form DNA which are grouped together in groups of three. When these codons are read as part of a gene, they provide the cell with the instructions to build a protein.
How are recessive and dominant genes represented?
We represent a dominant gene with a capital letter (R) and a recessive gene with a small letter (r).
Define homozygous
If the alleles of a particular gene are the same,the organism is described as homozygous for that gene
Represented as RR or rr
Define heterozygous
Heterozygous: having two different alleles of a particular gene or genes.We represent them as (Rr).
Define heredity
The transmission of characteristics from one generation to the next.
Define genetics
The study of how traits are passed from parent to offspring
Define genotype
Its complete set of genetic material
When does DNA replication occur?
This process takes place prior to cell division (mitosis and meiosis).
DNA replication process
The DNA molecule untwists.
The DNA molecule is unzipped by an enzyme called DNA helicase and prepared for replication by a molecule called RNA.
Two separate strands form.
Each side of the double helix acts as a template and free nucleotides present in the cytoplasm join each separated strand.
Each new section is zipped up.
DNA replication process makes one exact copy of each side of the original DNA.
Define transgenic organism
A transgenic organism is an organism with DNA from a different species inserted into its genome.
Define social and ethical considerations
Social considerations are factors that affect society and people
Ethical considerations are factors that take into account what is right and wrong.
IVF (in vitro fertilisation) social and ethical considerations
Social consideration: Not everyone can afford IVF so it is not an equitable treatment. Should some people miss out on having a baby just because they can not afford IVF?
Ethical consideration: It has been reported that some IVF doctors have been pressured to achieve high success rates and implant several fertilised eggs into a woman,instead of just one.This has resulted in multiple births, which is less safe for the mother and the babies.
IVF (in vitro fertilisation) advantages and disadvantages
Advantages:
Some people are unable to conceive a child naturally because of their age, health or other factors. IVF allows them to have children.
Disadvantages:
IVF is extremely expensive. Each round of treatment costs around $15 K. It is also invasive, the couple must undergo a number of procedures and the women requires regular injections of hormones.
What is IVF (In-vitro fertilisation)
A medical procedure whereby an egg is fertilised by sperm in a test tube or elsewhere outside the body.
how the Watson-Crick model of DNA explains:
– the exact replication of DNA
– changes in genes (mutation)
The Watson Crick Model is just the ‘double helix’ shape, and the idea that the information is coded in the order of the bases (letters) in the DNA strands. Understanding this allows us to more easily understand things like DNA replication (copying), as well as mutation (changes to the sequence).
Prostate gland structure & function
The prostate is a walnut-sized gland located between the bladder and the penis.
The prostate secretes fluid that nourishes and protects sperm.
Define genetic drift
The change in the frequency of an existing gene variant in a population due to random chance
Define somatic cells
Any cell of a living organism other than the reproductive cells.
