Apoptosis is programmed cell death, a controlled and orderly sequence of events by which a cell dismantles itself without damaging the cells around it.

Pyknosis is the condensation of the chromatin in the nucleus into a dense, tightly packed mass, an early feature of apoptosis.

What are blebs, and how do they arise?

Blebs are bulges of the plasma membrane that form as the cytoskeleton beneath it breaks down, and they pinch off as membrane-bound apoptotic bodies.

Karyorrhexis is the fragmentation of the condensed nucleus into pieces, which are then packaged into the apoptotic bodies.

Where is phosphatidylserine normally found in a healthy cell, and what happens to it during apoptosis?

It is normally confined to the inner leaflet of the plasma membrane, but during apoptosis it is moved to the outer surface where it can be detected from outside the cell.

OCR A-Level Biology B H422

The Developing Cell: Cell Division and Cell Differentiation

Topic overview The cell cycle and mitosis Apoptosis in growth and repair Stem cells and cell differentiation

The Developing Individual: Meiosis, Growth and Development

Topic overview Meiosis, haploid gametes and genetic variation The stages of meiosis Antenatal care and diet in pregnancy Alcohol, smoking and monitoring fetal growth Prenatal screening and karyotypes

The Development of Species: Evolution and Classification

Topic overview Classification and the species concept Evidence for classification and DNA barcoding Phylogenetic trees, hominids and the evolution of language Human adaptations, natural selection and evolution Plant adaptations and how they are investigated Measuring biodiversity and genetic diversity

Cells and Microscopy

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Water and Its Importance in Plants and Animals

Topic overview The properties of water Water as a transport medium and the composition of body fluids Detecting and measuring sugars and proteins Monomers, polymers and the carbohydrates Osmosis and water potential

Proteins and Enzymes

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Nucleic Acids

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Patterns of Inheritance

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Population Genetics and Epigenetics

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Gene Technologies

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The Principles and Importance of Homeostasis

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The Hormonal Control of Blood Glucose and the Management of Diabetes

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Kidney Functions and Malfunctions

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Respiratory Diseases and Treatment

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Cellular Respiration

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Metabolism and Exercise

Topic overview The consequences of exercise on the body Aerobic fitness and VO₂ max Training, F.I.T.T. factors and investigating fitness Enhancing athletic performance Haemoglobin and the transport of oxygen Oxygen dissociation curves of different respiratory pigments Oxygen deficit and oxygen debt The structure of skeletal muscle The sliding filament theory of muscle contraction

Pathogenic Microorganisms

Topic overview How pathogens cause communicable disease Tuberculosis HIV, AIDS and the structure of the virus Identifying bacteria: Gram staining and culture Epidemiology: incidence, prevalence and mortality Notifiable diseases and the control of HIV and TB

The Immune System

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Controlling Communicable Diseases

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Photosynthesis, Food Production and Management of the Environment

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Fertility and Assisted Reproduction

Topic overview The urinogenital systems and gonad histology Gametogenesis and the structure of the gametes Hormonal control of gametogenesis and the menstrual cycle Fertilisation and pregnancy testing The causes and issues of infertility Assisted reproduction techniques

The Effects of Ageing on the Reproductive System

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Plant Reproduction

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The Nervous System and the Identification and Consequences of Damage

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The Effect of Ageing on the Nervous System

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The Heart and Monitoring Heart Function

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Transport Systems in Mammals

Topic overview The closed double circulatory system Blood vessels and their microscopic structure Tissue fluid and capillary exchange Measuring and interpreting blood pressure

Gas Exchange in Mammals and Plants

Topic overview Tissues of the mammalian gas exchange system Gas exchange in the alveoli Pulmonary ventilation and lung volumes Expired air resuscitation Gas exchange and stomata in terrestrial plants

Transport Systems in Plants

Topic overview The need for transport systems in plants Vascular tissue in roots, stems and leaves Water uptake and movement through the plant Transpiration and Its Measurement Translocation in the Phloem

The Developing Cell: Cell Division and Cell Differentiation

Apoptosis in growth and repair

4 things to know
Components 01, 02 and 03

Overview

Recall questions on apoptosis as programmed cell death, pyknosis, blebs and karyorrhexis, how macrophages recognise phosphatidylserine, why apoptosis causes no inflammation unlike necrosis, its role in shaping digits and the nervous system, and its balance with mitosis in growth, tumours and repair.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

What happens to a cell, from the first visible changes to its removal, once apoptosis has been triggered?

Key term

Define apoptosis.

Process

What happens to the size and shape of a cell in the earliest stage of apoptosis?

Key term

What is pyknosis?

Questions from this subtopic

Each one with the model answer underneath.

1
Define apoptosis.
Model answer
Apoptosis is programmed cell death, a controlled and orderly sequence of events by which a cell dismantles itself without damaging the cells around it.
2
What happens to the size and shape of a cell in the earliest stage of apoptosis?
Model answer
The cell shrinks as its cytoskeleton is broken down, and it loses contact with the cells next to it.
3
What is pyknosis?
Model answer
Pyknosis is the condensation of the chromatin in the nucleus into a dense, tightly packed mass, an early feature of apoptosis.
4
What are blebs, and how do they arise?
Model answer
Blebs are bulges of the plasma membrane that form as the cytoskeleton beneath it breaks down, and they pinch off as membrane-bound apoptotic bodies.
5
Define karyorrhexis.
Model answer
Karyorrhexis is the fragmentation of the condensed nucleus into pieces, which are then packaged into the apoptotic bodies.
6
Where is phosphatidylserine normally found in a healthy cell, and what happens to it during apoptosis?
Model answer
It is normally confined to the inner leaflet of the plasma membrane, but during apoptosis it is moved to the outer surface where it can be detected from outside the cell.

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The Developing Cell: Cell Division and Cell Differentiation

The Developing Individual: Meiosis, Growth and Development

The Development of Species: Evolution and Classification

Cells and Microscopy

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Apoptosis in growth and repair

Overview

What you need to know

What happens to a cell, from the first visible changes to its removal, once apoptosis has been triggered?

Define apoptosis.

What happens to the size and shape of a cell in the earliest stage of apoptosis?

What is pyknosis?

Questions from this subtopic

Define apoptosis.

What happens to the size and shape of a cell in the earliest stage of apoptosis?

What is pyknosis?

What are blebs, and how do they arise?

Define karyorrhexis.

Where is phosphatidylserine normally found in a healthy cell, and what happens to it during apoptosis?

Other ways to work this

What is inside Levo

The 3-step method, run for you

Cram a whole paper in one sitting

Blank Blitz makes facts automatic

Build It gets the exam shape right

Test It catches misconceptions

Brain Breaks between sessions

Every question in The Developing Cell: Cell Division and Cell Differentiation, on a schedule.