Human bio

What are germline cells

They are found in ovaries and testis and can divide by mitosis then meiosis

What is cellular differentiation?

the process by which a cell becomes specialized to perform a specific function

What are somatic cells

Somatic cells are any cell in the body other than cells involved in reproduction, they divide by mitosis

What are stem cells?

unspecialised cells which can divide into many types of cells

How many chromosomes do humans have

They have 46 chromosomes divided into 23 pairs

What is differentiation

The process in which an un-specialised cells becomes specialised.

What are embryonic stem cells?

Unspecialised cells that can develop into any type of cell

What are the differences between embryonic and tissue stem cells

Embryonic are able to divide into any type of cell so are pluripotent.
Tissue stem cells are only able to divide into a limited amount of cells of the same type, they are multipotent

Where are tissue stem cells found?

Skin or bone marrow

Gives examples of both cells

Tissue - bone marrow, phagocytes, lymphocytes
Embryonic - gametes

What can stem cells in bone marrow do?

differentiate into blood cells, platelets, phagocytes and lymphocytes

What are the therapeutic and research uses of stem cells

Therapeutic- repair of damaged or diseased organs or tissues
Research- create model cells to study how diseases develop.

what do somatic cells divide by?

mitosis to produce more somatic stem cells

What do germline cells divide by?

Mitosis then meiosis to produce haploid gamete

Describe the antiparallel structure

-Runs in a 3' to 5' direction and opposite on other
-has deoxyribose at the 3' and 5' at phosphate at end

What are chromosomes composed of?

Tightly coiled DNA and packaged with associated proteins.

Describe the stages of replication of DNA?

- DNA strands unwound and unzipped
- The weak hydrogen bonds are then broken
- DNA polymerase requires a primer to start replication
- DNA polymerase adds free nucleotides
- DNA polymerase can only add nucleotides in a 3' to 5' direction, cause on to be replicated continuously and other in fragments
- Ligase then joins the completed stand.

what is a DNA polymerase

An enzyme which adds free nucleotides during DNA replication

What is a primer

A primer is a short complementary strand of nucleotides which binds to the 3' end of the template.

What are the stages of PCR?

Step 1 - separate the strands (92 to 98)
Step 2 - Cooled to allow primer to bind to target sequence (50-65)
Step 3 - Heated to allow heat tolerant DNA polymerase to replicate (70-80)

What are the applications of PCR?

Used to amplify DNA and can be used to confirm the presence of of individuals at crime scenes

What does gene expression involve?

transcription then translation.
Only a fraction of the genes in a cell are expressed.

What are the differences between DNA and RNA?

DNA: double-stranded RNA: single-stranded
DNA has deoxyribose sugar RNA has ribose sugar DNA has bases: A, T, G, C RNA has bases: A, U, G, C

What are the two stages that genes are expressed

Transcription then translation

What order is DNA Synthesized?

DNA to mRNA to tRNA

Where does translation occur?

ribosome

where does transcription take place

nucleus

Describe transcription

- RNA polymerase unwinds and unzips the double helix
- Free RNA nucleotides against DNA nucleotides, which join to form he primary transcript
- The introns and exons undergo RNA splicing which removes the introns.

What is translation

- The production of a polypeptide at a ribosome using information encoded in mRNA

what is alternative RNA splicing

some exons may excluded or included in mature transcript

What are introns?

non-coding regions of DNA

what are exons

coding regions of DNA

Describe stages in translation

-The mRNA molecule travels through the cytoplasm and attaches to the ribosome.
-tRNA molecules transport specific amino acids to the ribosome.
-Each mRNA codon codes for a specific amino acid.
-The first codon of an mRNA molecule is a start codon. This signals the beginning of translation.
-The anti-codons and codons match up and form complementary base pairs.
-Peptide bonds form between amino acids to form the polypeptide
-Used tRNA molecules exit the ribosome and collect another specific amino acid.
-The last codon of an mRNA molecule is a stop codon which signals the end of translation.

What is a polypeptide bond?

A chain of amino acids held together by peptide bonds

Where are Anticodons found?

On a tRNA molecule
They which codes for a specific amino acid

How is the 3D shape of a protein formed

As a result of the polypeptide chain folding

Label the parts of the tRNA molecule

Name the single gene mutations

- substitution
- Deletion
- insertion

Describe the single nucleotide mutations

- Missense: When one amino acid is being changed for another, may result in a non-functional protein or little affect on protein
- Nonsense: Results in a stop codon being produced , which results in a shorter protein.
-Splice site mutations: results in some introns being retained or some exons not being included in mature transcript.

What is a frame shift mutation?

- Frame-shift mutation results in all the codons after the mutations being changed, this has a major affect on protein

Name and describe the chromosome mutations

- Duplication: occurs when a section of a chromosome is added from its homologous partner.
- Deletion: is where a section of a chromosome is removed
- Inversion: is where a section of a chromosome is reversed
- Translocation: is where a section of a chromosome is added to another chromosome that is not its homologous partner

What is a genome?

An organisms entire hereditary information encoded in DNA, can be used to predict the likelihood of developing certain diseases

What is bioinformatics

The use of computers and statistics to compare sequence data

What is pharmacogenetics

The use of a persons genome information in the choice of effective drugs

What is a metabolic pathway?

series of chemical reactions that occur within a cell

What are catabolic reactions?

Catabolic reactions break down large molecules into smaller molecules and release energy

What are anabolic reactions?

Anabolic reactions build up large molecules from small molecules and require energy

What is metabolism?

metabolism is all the chemical reactions that take place in cells.

How do enzymes work?

Lower activation energy needed to start a chemical reaction

When there is a faulty enzyme what steps can be taken

They can have reversible and alternative pathways.

What is induced fit?

When the active site changes its shape to better fit the substrate.

what is affinity?

The attraction between the active site of an enzyme and its substrate

what is activation energy?

energy needed to start a reaction

Describe how concentration effects on inhibitors

Competitive inhibitor: an increase in concentration speeds up the rate of reaction
Non-competitive inhibitor: increase in concentration does not increase reaction rate.

What is feedback inhibition?

When the end product inhibits an enzyme hat catalysed a reaction earlier in the pathway

Where does glycolysis occur?

cytoplasm

How are dehydrogenase enzymes used in glycolysis?

During the energy pay off phase, dehydrogenase enzymes remove hydrogen ions and electrons, which combine with coenzyme NAD to form NADH.

what is Coenzyme A?

substance that carries acetyl groups into citric acid cycle

what is NAD?

coenzyme which carries hydrogen and electrons from glycolysis and citric acid cycle to electron transport chain

Where does the citric acid cycle occur?

Matrix of mitochondria

Describe stages in citric acid cycle

- The pyruvate enters the matrix of the mitochondria and carbon dioxide is removed.
- The removal of carbon forms an acetyl group. This acetyl group combines with coenzyme A to form acetyl coenzyme A
- Oxaloacetate combines with acetyl coenzyme A to form citrate.
- citrate undergoes a series of reactions to release carbon dioxide.
- Dehydrogenase enzymes remove hydrogen ions and electrons forming NADH. The high-energy electrons are passed to the electron transport chain.

Where does the electron transport chain occur?

inner membrane of mitochondria

Describe stages of electron transport chain?

- NADH release the hydrogen ions and electrons into the transport chain
- electrons are passed along the wall of the electron transport chain
- The energy is used to pump hydrogen ions across inner membrane
- Hydrogen ions and electrons combine with oxygen to form water

What is ATP synthase and how does it work?

a membrane-bound enzyme which that synthesises ATP from ADP + pi

Fermentation

Fermentation occurs in the absence of oxygen after glycolysis

What happens to pyruvate during vigorous exercise

Muscle cells do not receive enough oxygen, therefor pyruvate is converted into lactate

What happens when there is a build up of lactate?

muscle fatigue
During recovery the oxygen debt is re-paid

Slow twitch muscles

Useful for long-distance activities, They rely on aerobic respiration and have many mitochondria and more myoglobin

fast twitch muscle fibers

They are useful for activities such as sprinting, they generate ATP through only glycolysis , their major fuel is glycogen

Where is sperm produced?

seminiferous tubules

Where is testosterone produced?

The interstitial cell

What do the prostate glands and seminal vesicles secrete?

Fluids that maintain the mobility and viability of the sperm

Where is a zygote formed?

oviduct

What happens during puberty?

The hypothalamus in the brain releases releaser hormone that targets the pituitary gland.

What hormones does the pituitary gland secrete in men and women?

Women: LH and FSH
Men: FSH and ICSH

What is a follicle?

structure that surrounds and protects the developing ovum and produces oestrogen

What are the roles of these hormones in women

FSH: stimulates the development of the follicle
LH: triggers ovulation

What are the roles of these hormones in men

FSH promotes sperm production on interstitial cells
ISCH: promotes testosterone production in seminiferous tubules

What happens when there is too much testosterone?

Negative feedback

Describe negative feedback of testosterone

When testosterone level increases over a certain level the testosterone inhibits ICSH and FSH from pituitary gland

How long is the menstrual cycle?

28 days

what are the two phases of the menstrual cycle

follicular phase and luteal phase

What happens at peak levels oestrogen

stimulates a surge of LH by the pituitary gland

Describe continuous and cyclical fertility

Men are continuously fertile as they continuously produce sperm

Women are cyclical as they are only fertile for a few days in the menstrual cycle

How can women's fertile periods be identified?

- The body temperature increases by 0.5 degrees
- her cervical mucus becomes thin and watery
- Ovulation typically occurs 10 to 16 days before the start of a period

How would oestrogen/progesterone levels change if fertilisation occurred?

Progestogen levels remain high

How would oestrogen/progesterone levels change if fertilisation didn't occur?

corpus luteum degenerates and progesterone and oestrogen levels decrease. The decrease in these hormones result in the onset of menstruation

Describe negative feedback of menstrual cycle?

High progesterone negatively feedback effect pituitary gland, resulting in the inhibition of FSH and LH

How do ovulatory drugs work?

Some drugs work by preventing the negative feedback effect of oestrogen on FSH
Some drugs mimic the the action of FSH and LH

What is the problem with these ovulatory drugs drugs?

they can cause super ovulation (multiple births)

Name treatments of infertility?

IVF
Artificial insemination
Ovulatory drugs
ICSI

Describe the process of IVF

1. Caused by blockage in oviduct
2. Hormones are given to stimulate ovulation in the female
3. Eggs are surgically removed
4. Sperm cells are mixed with ova in a dish
5. The fertilised eggs are incubated before being transferred back to the uterus

Describe the process of artificial insemination?

1. Used when sperm has a low count
2. sperm is collected
3. sperm can be tested to see if sperm is sterile
4. A donor may be needed
5. Sperm is inserted into uterus from a syringe

Describe the process of ICSI?

1. Sample of sperm is taken
2. The head of the active sperm is drawn into a needle
3. Then directly injected into the ovum to achieve fertilisation

Name physical methods of contraception

- condom
- intra-uterine device (IUD)
- vasectomy

Name and describe chemical methods of contraception?

The pill: Contains synthetic progestogen and oestrogen that mimics the negative feedback, preventing the release of FSH and LH
Mini pill: Thickens cervical mucus, which prevents sperm from entering the uterus
The morning after pill: Contains synthetic progestogen and oestrogen, thickening cervical mucus and stops sperm from entering the uterus

explain the difference between continuous and cyclical fertile

-women are cyclical fertile as they for a few days in the menstrual cycle
- men are continuous as they constantly produce sperm

state techniques used to monitor babies health

ultra scans, blood/urine tests

Name antenatal procedures?

- Amniocentesis
- chorionic villus sampling (CVS)
- ultrasound scanning

What is the purpose of antenatal screening?

Identifies risks of a disorder before birth so that further tests and a prenatal diagnosis can be offered